Recently, the surface chemical functionalization and morphology control of precious metal nanostructures have been recognized as two efficient strategies for improving their electroactivity and/or selectivity. In this...Recently, the surface chemical functionalization and morphology control of precious metal nanostructures have been recognized as two efficient strategies for improving their electroactivity and/or selectivity. In this work, 1, 10-phenanthroline monohydrate(PM) functionalized Pt nanodendrites(Pt-NDs) on carbon cloth(CC)(denoted as PM@Pt-NDs/CC) and polyethylenimine(PEI) functionalized Pt-NDs on CC(denoted as PEI@Pt-NDs/CC) are successfully achieved by immersing Pt-NDs/CC into PM and PEI aqueous solutions, respectively. PEI functionalization of Pt-NDs/CC improves its electroactivity for hydrogen evolution reaction(HER) due to local proton enrichment whereas PM functionalization of Pt-NDs/CC improves its electroactivity for formic acid oxidation reaction(FAOR) by facilitating dehydrogenation pathway. With such high activity, a two-electrode electrolyzer is assembled using PM@Pt-NDs/CC as the anodic electrocatalyst and PEI@Pt-NDs/CC as the cathodic electrocatalyst for electrochemical reforming of formic acid, which only requires 0.45 V voltage to achieve the current density of 10 mA cm^(-1) for highpurity hydrogen production, much lower than conventional water electrolysis(1.59 V). The work presents an example of interfacial engineering enhancing electrocatalytic activity and indicates that electrochemical reforming of formic acid is an energy-saving electrochemical method for high-purity hydrogen production.展开更多
Alloying and nanostructuring are two strategies used to facilitate the efficient electrocatalysis of the oxygen reduction reaction(ORR)by Pt,where the high index surfaces(HISs)of Pt exhibit superior activity for ORR.H...Alloying and nanostructuring are two strategies used to facilitate the efficient electrocatalysis of the oxygen reduction reaction(ORR)by Pt,where the high index surfaces(HISs)of Pt exhibit superior activity for ORR.Here,we report the fabrication of PtCu3 nanodendrites possessing rich spiny branches exposing n(111)×(110)HISs.The dendrites were formed through an etching‐modulated seeding and growing strategy.Specifically,an oxidative atmosphere was initially applied to form the concaved nanocubes of the Pt‐Cu seeds,which was then switched to an inert atmosphere to promote an explosive growth of dendrites.Separately,the oxidative or inert atmosphere failed to produce this hyperbranched structure.Electrochemical dealloying of the PtCu3 nanodendrites produced Pt3Cu shells with Pt‐rich surfaces where HIS‐exposed dendrite structures were maintained.The resulting PtCu_(3)@Pt_(3)Cu@Pt nanodendrites in 0.1 M HClO4 exhibited excellent mass and area specific activities for ORR,which were 14 and 24 times higher than that of commercial Pt/C,respectively.DFT calculations revealed that Cu alloying and HISs both contributed to the significantly enhanced activity of Pt,and that the oxygen binding energy on the step sites of HISs on the PtCu_(3)@Pt_(3)Cu@Pt nanodendrites approached the optimal value to achieve a near peak‐top ORR activity.展开更多
Rational synthesis of a new class of electrocatalysts with high-performance and low-cost is of great significance for future fuel cell devices. Herein, we demonstrate a general one-step simultaneous reduction method t...Rational synthesis of a new class of electrocatalysts with high-performance and low-cost is of great significance for future fuel cell devices. Herein, we demonstrate a general one-step simultaneous reduction method to prepare carbon-supported Pd M（M = Co, Fe, Ni） alloyed nanodendrites with the assistance of oleylamine and octadecylene. The morphology, structure and composition of the obtained Pd M nanodendrites/C catalysts have been fully characterized. The combination of the dendritic structural feature and alloyed synergy offer higher atomic utilization efficiency, excellent catalytic activity and enhanced stability for the formic acid oxidation reaction（FAOR）. Strikingly, the as-synthesized Pd Co nanodendrites/C catalyst could afford a mass current density of 2467.7 A g, which is almost 3.53 and 10.4 times higher than those of lab-made Pd/C sample(698.3 A g) and commercial Pd/C catalyst(237.6 A g), respectively. Furthermore, the PdC o nanodendrites/C catalyst also exhibit superior stability relative to the Pd/C catalysts, make it a promising anodic electrocatalyst in practical fuel cells in the future. Additionally, the present feasible synthetic approach is anticipated to provide a versatile strategy toward the preparation of other metal alloy nanodendrites/carbon nanohybrids.展开更多
We report a solvothermal method preparation of dendritic Pd nanoparticles （DPNs） and spherical Pd nanoparticles （SPNs） supported on reduced graphene oxide （RGO）. Drastically different morphologies of Pd NPs with...We report a solvothermal method preparation of dendritic Pd nanoparticles （DPNs） and spherical Pd nanoparticles （SPNs） supported on reduced graphene oxide （RGO）. Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide （GO） un- der mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst.展开更多
The development of effective and stable electrocatalysts for the hydrogen evolution reaction(HER)in acidic electrolytes is a significant challenge.In this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell wer...The development of effective and stable electrocatalysts for the hydrogen evolution reaction(HER)in acidic electrolytes is a significant challenge.In this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell were successfully synthesized by a two-step wet chemical method.This open three-dimensional(3D)dendritic structure exhibited exceptional electrocatalytic characteristics,exposing as many active sites as feasible.Furthermore,by alloying Ir with Pt on the surface,catalytic activity was greatly enhanced while ensuring extremely high stability.Iridium surface-enriched platinum nanodendritic catalysts(Pt@PtIr NDs)outperformed the control samples and the commercial catalysts.In acidic HER test,Pt@PtIr NDs had a lower overpotential(22 mV)than Pt NDs(26 mV)and commercial Pt/C(31 mV)at 10 mA/cm^(2),and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h,which was much superior to the performance of commercial Pt/C(10 h)under identical test conditions.This study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER.展开更多
The single-pot production of Pd@Pt core-shell structures is a promising approach as it offers large surface area,catalytic capability,and stability.In this work,we established a single-pot process to produce Pd@Pt cor...The single-pot production of Pd@Pt core-shell structures is a promising approach as it offers large surface area,catalytic capability,and stability.In this work,we established a single-pot process to produce Pd@Pt core-shell nanodendrites with tunable composition,shape and size for optimal electrochemical activity.Pd@Pt nanodendrites with diverse compositions were synthesized by tuning the ratios of Pd and Pt sources in an aqueous environment using cetyltrimethylammonium chloride,which functioned as both the surfactant and the reducing agent at an elevated temperature(90°C).The synthesized Pd5@Pt5 nanodendrites showed exceptional electrochemical action toward the methanol oxidation reaction related with another compositional Pd@Pt nanodendrites and conventional Pt/C electrocatalysts.In addition,Pd5@Pt5 nanodendrites exhibited good CO tolerance owing to their surface features and the synergistic effect among Pt and Pd.Meanwhile,nanodendrites with a Pt-rich surface provided exceptional catalytic active sites.Compared with the conventional Pt/C electrocatalyst,the anodic peak current obtained by Pd5@Pt5 nanodendrites was 3.74 and 2.18 times higher in relations of mass and electrochemical active surface area-normalized current density,respectively.This approach offers an attractive strategy to design electrocatalysts with unique structures and outstanding catalytic performance and stability for electrochemical energy conversion.展开更多
Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effec...Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effective strategy for improving their catalytic activity and durability. In this work, well-defined Rh nanodendrites with very thin triangular branches as subunits are synthesized using a facile diethylene glycol reduction method, assisted by polyethyleneimine as a complex-forming agent and surfactant. For the first time, the methanol oxidation reaction （MOR） on Rh nanocrystals with a well-defined morphology is investigated using various electrochemical techniques in an alkaline medium. Unexpectedly, the as-prepared Rh nanodendrites, with ultrathin nanosheet subunits, exhibit superior electrocatalytic activity and durability during the MOR in an alkaline medium, indicating that Rh nanocrystals with specific morphology may be highly promising alternatives to Pt electrocatalysts in the MOR in an alkaline medium.展开更多
A facile and green approach has been developed for the in situ synthesis of hybrid nanomaterials based on dendrite-shaped Pd nanostructures supported on graphene （RG）. The as-synthesized hybrid nanomaterials （RG-Pd...A facile and green approach has been developed for the in situ synthesis of hybrid nanomaterials based on dendrite-shaped Pd nanostructures supported on graphene （RG）. The as-synthesized hybrid nanomaterials （RG-PdnDs） have been thoroughly characterized by high resolution transmission electron microscopy, X-ray photoelectron spectroscop）~ atomic force microscop）~ Raman spectroscopy and electrochemical techniques. The mechanism of formation of such dendrite- shaped Pd nanostructures on the graphene support has been elucidated using transmission electron microscopy （TEM） measurements. The RG induces the formation of, and plays a decisive role in shaping, the dendrite morphology of Pd nanostructures on its surface. Cyclic voltammetry and chronoamperometry techniques have been employed to evaluate the electrochemical performance of RG-PdnDs towards oxidation of methanol. The electrochemical （EC） activities of RG-PdnDs are compared with graphene-supported spherical-shaped Pd nanostructures, Pd nanodendrites alone and a commercial available Pd/C counterpart. The combined effect of the graphene support and the dendrite morphology of RG-PdnDs triggers the high electrocatalytic activity and results in robust tolerance to CO poisoning.展开更多
Benzaldehyde byproduct is an imperative intermediate in the production of fine chemicals and additives.Tuning selectivity to benzaldehyde is therefore critical in alcohol oxidation reactions at the industrial level.He...Benzaldehyde byproduct is an imperative intermediate in the production of fine chemicals and additives.Tuning selectivity to benzaldehyde is therefore critical in alcohol oxidation reactions at the industrial level.Herein,we report a simple but innovative method for the synthesis of palladium hydride and nickel palladium hydride nanodendrites with controllable morphology,high stability,and excellent catalytic activity.The synthesized dendrites can maintain the palladium hydride phase even after their use in the chosen catalytic reaction.Remarkably,the high surface area morphology and unique interaction between nickel-rich surface and palladium hydride (β-phase) of these nanodendrites are translated in an enhanced catalytic activity for benzyl alcohol oxidation reaction.Our Ni/PdH0.43 nanodendrites demonstrated a high selectivity towards benzaldehyde of about 92.0% with a conversion rate of 95.4%,showing higher catalytic selectivity than their PdH0.43 counterparts and commercial Pd/C.The present study opens the door for further exploration of metal/metal-hydride nanostructures as next-generation catalytic materials.展开更多
High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catal...High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon(Pt NDs).Owing to the large elect roc he mically active area and the exposed(111) facet of Pt,Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈22 mV/dec in acidic media.In addition,the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings.Moreover,Pt NDs exhibits excellent lo ng-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production,while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance.Considering the superiority of catalytic activity and stability,this Pt NDs present great potentiality towards practical hydrogen production application.展开更多
We report on the successful fabrication of highly branched Cu S nanocrystals by laser-induced photochemical reaction.Surprisingly, the single-crystalline nature with preferential alignment of the（107） orientation ca...We report on the successful fabrication of highly branched Cu S nanocrystals by laser-induced photochemical reaction.Surprisingly, the single-crystalline nature with preferential alignment of the（107） orientation can be well improved during the moderate growth process. The branch length drastically increases from about 5 nm to 6 μm with an increase of photochemical reaction time（0-40 min）. The absorption spectra of as-prepared Cu S nanodendrites show that localized surface plasmon resonance（LSPR） peaks can be modulated from about 1037 nm to 1700 nm with an increase of branch length. Our results have a promising potential for photodynamic therapy and biological imaging application.展开更多
We report a fast in situ seeding approach based on zinc（II） porphyrin （ZnP） under white light irradiation, leading to uniform spherical platinum nanodendrites with tunable sizes. The platinum nanodendrites exhibit...We report a fast in situ seeding approach based on zinc（II） porphyrin （ZnP） under white light irradiation, leading to uniform spherical platinum nanodendrites with tunable sizes. The platinum nanodendrites exhibit significantly improved electrocatalytic activities toward oxygen reduction reaction （ORR） and methanol oxidation reaction （MOR） compared with commercial platinum black.展开更多
The noble metal rhodium(Rh)nanostructures have wide applications in catalysis and electrocatalysis.In this work,a series of Rh Ni alloy nanostructures with different Rh/Ni atomic ratios can be synthesized by one-step ...The noble metal rhodium(Rh)nanostructures have wide applications in catalysis and electrocatalysis.In this work,a series of Rh Ni alloy nanostructures with different Rh/Ni atomic ratios can be synthesized by one-step wet chemical method.By adjusting Rh^(Ⅲ)/Ni^(iⅡ)feed ratio,high-quality one-dimensional Rh_(1)Ni_(1)alloy nanodendrite assemblies(Rh_(1)Ni_(1)-NDs-As)can be synthesized selectively.Electrochemical measurements show that the introduction of Ni can enhance the electroactivity of Rh nanomaterials for methanol oxidation reaction(MOR)in alkaline media.For potential practical application,Rh_(1)Ni_(1)-NDs-As reveals improved electroactivity and durability for MOR compared to commercial Rh nanoparticle due to the particular morphology,Ni-doping,high electrochemical active area,and excellent anti-poison ability.Considering the facial synthesis and high electroactivity/durability,Rh_(1)Ni_(1)-NDs-As may be promising anode catalysts in direct methanol fuel cells.展开更多
Rational design has been widely used to develop high-performance metal selenides-based electrode materials for supercapacitors.In this study,we develop a facile one-step solvothermal approach to synthesize binder-free...Rational design has been widely used to develop high-performance metal selenides-based electrode materials for supercapacitors.In this study,we develop a facile one-step solvothermal approach to synthesize binder-free Ni_(3)Se_(2) nanodendrite arrays grown on nickel foam as advanced positive electrodes for supercapacitors.Our Ni_(3)Se_(2) nanodendrite arrays on nickel foam exhibit a specific capacitance of 1234 Fg^(-1)(3.70 F cm^(-2))at a current density of 1 Ag^(-1) and a great rate capability,which is benefited from the excellent electrical conductivity and unique hierarchical nano-dendritic structure.Furthermore,an asymmetric supercapacitor device was assembled using activated carbon as the negative electrode and the Ni_(3)Se_(2) nanodendrite arrays on nickel foam as the positive electrode,obtaining a high energy density of 22.3 W h kg^(-1) at a power density of 160.4 W kg^(-1).展开更多
基金sponsored by Natural Science Foundation of Shaanxi Province (2020JZ-23)the Fundamental Research Funds for the Central Universities (GK201901002, GK201701007 and GK201902014)the 111 Project (B14041)。
文摘Recently, the surface chemical functionalization and morphology control of precious metal nanostructures have been recognized as two efficient strategies for improving their electroactivity and/or selectivity. In this work, 1, 10-phenanthroline monohydrate(PM) functionalized Pt nanodendrites(Pt-NDs) on carbon cloth(CC)(denoted as PM@Pt-NDs/CC) and polyethylenimine(PEI) functionalized Pt-NDs on CC(denoted as PEI@Pt-NDs/CC) are successfully achieved by immersing Pt-NDs/CC into PM and PEI aqueous solutions, respectively. PEI functionalization of Pt-NDs/CC improves its electroactivity for hydrogen evolution reaction(HER) due to local proton enrichment whereas PM functionalization of Pt-NDs/CC improves its electroactivity for formic acid oxidation reaction(FAOR) by facilitating dehydrogenation pathway. With such high activity, a two-electrode electrolyzer is assembled using PM@Pt-NDs/CC as the anodic electrocatalyst and PEI@Pt-NDs/CC as the cathodic electrocatalyst for electrochemical reforming of formic acid, which only requires 0.45 V voltage to achieve the current density of 10 mA cm^(-1) for highpurity hydrogen production, much lower than conventional water electrolysis(1.59 V). The work presents an example of interfacial engineering enhancing electrocatalytic activity and indicates that electrochemical reforming of formic acid is an energy-saving electrochemical method for high-purity hydrogen production.
文摘Alloying and nanostructuring are two strategies used to facilitate the efficient electrocatalysis of the oxygen reduction reaction(ORR)by Pt,where the high index surfaces(HISs)of Pt exhibit superior activity for ORR.Here,we report the fabrication of PtCu3 nanodendrites possessing rich spiny branches exposing n(111)×(110)HISs.The dendrites were formed through an etching‐modulated seeding and growing strategy.Specifically,an oxidative atmosphere was initially applied to form the concaved nanocubes of the Pt‐Cu seeds,which was then switched to an inert atmosphere to promote an explosive growth of dendrites.Separately,the oxidative or inert atmosphere failed to produce this hyperbranched structure.Electrochemical dealloying of the PtCu3 nanodendrites produced Pt3Cu shells with Pt‐rich surfaces where HIS‐exposed dendrite structures were maintained.The resulting PtCu_(3)@Pt_(3)Cu@Pt nanodendrites in 0.1 M HClO4 exhibited excellent mass and area specific activities for ORR,which were 14 and 24 times higher than that of commercial Pt/C,respectively.DFT calculations revealed that Cu alloying and HISs both contributed to the significantly enhanced activity of Pt,and that the oxygen binding energy on the step sites of HISs on the PtCu_(3)@Pt_(3)Cu@Pt nanodendrites approached the optimal value to achieve a near peak‐top ORR activity.
基金financial supports from NSFC(no.21576139,21503111 and 21376122)Natural Science Foundation of Jiangsu Province(BK20171473)+2 种基金Natural Science Foundation of Jiangsu Higher Education Institutions of China(16KJB150020)National and Local Joint Engineering Research Center of Biomedical Functional Materialsa project sponsored by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Rational synthesis of a new class of electrocatalysts with high-performance and low-cost is of great significance for future fuel cell devices. Herein, we demonstrate a general one-step simultaneous reduction method to prepare carbon-supported Pd M（M = Co, Fe, Ni） alloyed nanodendrites with the assistance of oleylamine and octadecylene. The morphology, structure and composition of the obtained Pd M nanodendrites/C catalysts have been fully characterized. The combination of the dendritic structural feature and alloyed synergy offer higher atomic utilization efficiency, excellent catalytic activity and enhanced stability for the formic acid oxidation reaction（FAOR）. Strikingly, the as-synthesized Pd Co nanodendrites/C catalyst could afford a mass current density of 2467.7 A g, which is almost 3.53 and 10.4 times higher than those of lab-made Pd/C sample(698.3 A g) and commercial Pd/C catalyst(237.6 A g), respectively. Furthermore, the PdC o nanodendrites/C catalyst also exhibit superior stability relative to the Pd/C catalysts, make it a promising anodic electrocatalyst in practical fuel cells in the future. Additionally, the present feasible synthetic approach is anticipated to provide a versatile strategy toward the preparation of other metal alloy nanodendrites/carbon nanohybrids.
文摘We report a solvothermal method preparation of dendritic Pd nanoparticles （DPNs） and spherical Pd nanoparticles （SPNs） supported on reduced graphene oxide （RGO）. Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide （GO） un- der mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst.
基金the National Key R&D Program of China(No.2018YFA0704502)the National Key Research and Development Project of China(No.2022YFA1503900)+1 种基金the NSFC(Nos.22033008 and 22220102005)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZZ103).
文摘The development of effective and stable electrocatalysts for the hydrogen evolution reaction(HER)in acidic electrolytes is a significant challenge.In this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell were successfully synthesized by a two-step wet chemical method.This open three-dimensional(3D)dendritic structure exhibited exceptional electrocatalytic characteristics,exposing as many active sites as feasible.Furthermore,by alloying Ir with Pt on the surface,catalytic activity was greatly enhanced while ensuring extremely high stability.Iridium surface-enriched platinum nanodendritic catalysts(Pt@PtIr NDs)outperformed the control samples and the commercial catalysts.In acidic HER test,Pt@PtIr NDs had a lower overpotential(22 mV)than Pt NDs(26 mV)and commercial Pt/C(31 mV)at 10 mA/cm^(2),and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h,which was much superior to the performance of commercial Pt/C(10 h)under identical test conditions.This study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER.
基金the Basic Science Research Program of the National Research Foundation(NRF)of Korea(Nos.2019R1A6A1A11053838,2022R1A4A3033528,and 2022R1F1A1063285)Korea Agency for Infrastructure Technology Advancement(KAIA)funded by the Ministry of Land,Infrastructure,and Transport(No.21CTAP-C163795-01)Prof.M.Y.Choi acknowledges the Korea Basic Science Institute(National Research Facilities and Equipment Center)grant funded by the Ministry of Education(Nos.2019R1A6C1010042 and 2021R1A6C103A427).
文摘The single-pot production of Pd@Pt core-shell structures is a promising approach as it offers large surface area,catalytic capability,and stability.In this work,we established a single-pot process to produce Pd@Pt core-shell nanodendrites with tunable composition,shape and size for optimal electrochemical activity.Pd@Pt nanodendrites with diverse compositions were synthesized by tuning the ratios of Pd and Pt sources in an aqueous environment using cetyltrimethylammonium chloride,which functioned as both the surfactant and the reducing agent at an elevated temperature(90°C).The synthesized Pd5@Pt5 nanodendrites showed exceptional electrochemical action toward the methanol oxidation reaction related with another compositional Pd@Pt nanodendrites and conventional Pt/C electrocatalysts.In addition,Pd5@Pt5 nanodendrites exhibited good CO tolerance owing to their surface features and the synergistic effect among Pt and Pd.Meanwhile,nanodendrites with a Pt-rich surface provided exceptional catalytic active sites.Compared with the conventional Pt/C electrocatalyst,the anodic peak current obtained by Pd5@Pt5 nanodendrites was 3.74 and 2.18 times higher in relations of mass and electrochemical active surface area-normalized current density,respectively.This approach offers an attractive strategy to design electrocatalysts with unique structures and outstanding catalytic performance and stability for electrochemical energy conversion.
基金This work was supported by National Natural Science Foundation of China （No. 21473111）, Natural Science Foundation of Shaanxi Province （No. 2015JM2043）,and Fundamental Research Funds for the Central Universities （Nos. GK201602002 and GK201503037）.
文摘Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effective strategy for improving their catalytic activity and durability. In this work, well-defined Rh nanodendrites with very thin triangular branches as subunits are synthesized using a facile diethylene glycol reduction method, assisted by polyethyleneimine as a complex-forming agent and surfactant. For the first time, the methanol oxidation reaction （MOR） on Rh nanocrystals with a well-defined morphology is investigated using various electrochemical techniques in an alkaline medium. Unexpectedly, the as-prepared Rh nanodendrites, with ultrathin nanosheet subunits, exhibit superior electrocatalytic activity and durability during the MOR in an alkaline medium, indicating that Rh nanocrystals with specific morphology may be highly promising alternatives to Pt electrocatalysts in the MOR in an alkaline medium.
文摘A facile and green approach has been developed for the in situ synthesis of hybrid nanomaterials based on dendrite-shaped Pd nanostructures supported on graphene （RG）. The as-synthesized hybrid nanomaterials （RG-PdnDs） have been thoroughly characterized by high resolution transmission electron microscopy, X-ray photoelectron spectroscop）~ atomic force microscop）~ Raman spectroscopy and electrochemical techniques. The mechanism of formation of such dendrite- shaped Pd nanostructures on the graphene support has been elucidated using transmission electron microscopy （TEM） measurements. The RG induces the formation of, and plays a decisive role in shaping, the dendrite morphology of Pd nanostructures on its surface. Cyclic voltammetry and chronoamperometry techniques have been employed to evaluate the electrochemical performance of RG-PdnDs towards oxidation of methanol. The electrochemical （EC） activities of RG-PdnDs are compared with graphene-supported spherical-shaped Pd nanostructures, Pd nanodendrites alone and a commercial available Pd/C counterpart. The combined effect of the graphene support and the dendrite morphology of RG-PdnDs triggers the high electrocatalytic activity and results in robust tolerance to CO poisoning.
文摘Benzaldehyde byproduct is an imperative intermediate in the production of fine chemicals and additives.Tuning selectivity to benzaldehyde is therefore critical in alcohol oxidation reactions at the industrial level.Herein,we report a simple but innovative method for the synthesis of palladium hydride and nickel palladium hydride nanodendrites with controllable morphology,high stability,and excellent catalytic activity.The synthesized dendrites can maintain the palladium hydride phase even after their use in the chosen catalytic reaction.Remarkably,the high surface area morphology and unique interaction between nickel-rich surface and palladium hydride (β-phase) of these nanodendrites are translated in an enhanced catalytic activity for benzyl alcohol oxidation reaction.Our Ni/PdH0.43 nanodendrites demonstrated a high selectivity towards benzaldehyde of about 92.0% with a conversion rate of 95.4%,showing higher catalytic selectivity than their PdH0.43 counterparts and commercial Pd/C.The present study opens the door for further exploration of metal/metal-hydride nanostructures as next-generation catalytic materials.
基金financial support by the National Natural Science Foundation of China(Nos.51573201,51501209 and 201675165)NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(No.U1709205)+6 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22000000)Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201640)Science and Technology Major Project of Ningbo(Nos.2016S1002,2016B10038)International S&T Cooperation Program of Ningbo(No.2017D10016)for financial supportthe Chinese Academy of Sciences for Hundred Talents ProgramChinese Central Government for Thousand Young Talents Program3315 Program of Ningbo。
文摘High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon(Pt NDs).Owing to the large elect roc he mically active area and the exposed(111) facet of Pt,Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈22 mV/dec in acidic media.In addition,the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings.Moreover,Pt NDs exhibits excellent lo ng-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production,while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance.Considering the superiority of catalytic activity and stability,this Pt NDs present great potentiality towards practical hydrogen production application.
基金Project supported by National Natural Science Foundation of China(Grant Nos.11575102,11105085,11405098,and 11375108)the Fundamental Research Funds of Shandong University,China(Grant No.2015JC007)
文摘We report on the successful fabrication of highly branched Cu S nanocrystals by laser-induced photochemical reaction.Surprisingly, the single-crystalline nature with preferential alignment of the（107） orientation can be well improved during the moderate growth process. The branch length drastically increases from about 5 nm to 6 μm with an increase of photochemical reaction time（0-40 min）. The absorption spectra of as-prepared Cu S nanodendrites show that localized surface plasmon resonance（LSPR） peaks can be modulated from about 1037 nm to 1700 nm with an increase of branch length. Our results have a promising potential for photodynamic therapy and biological imaging application.
基金Acknowledgements This work was partially supported by the National Basic Research Program （973 Program） of China （No. 2012CB215500）, the National High-tech R＆D Program（863 Program） of China （No. 2011AA11A273）, and the National Natural Science Foundation of China （NSFC, Nos. 21003114 and 21103163）. The authors thank Professor John A. Shelnutt at Georgia University, USA for fruitful discussions.
文摘We report a fast in situ seeding approach based on zinc（II） porphyrin （ZnP） under white light irradiation, leading to uniform spherical platinum nanodendrites with tunable sizes. The platinum nanodendrites exhibit significantly improved electrocatalytic activities toward oxygen reduction reaction （ORR） and methanol oxidation reaction （MOR） compared with commercial platinum black.
基金sponsored by the National Natural Science Foundation of China(21875133)Natural Science Foundation of Shaanxi Province(2020JZ-23)Key Research and Development Program of Shaanxi(2020SF-355)。
文摘The noble metal rhodium(Rh)nanostructures have wide applications in catalysis and electrocatalysis.In this work,a series of Rh Ni alloy nanostructures with different Rh/Ni atomic ratios can be synthesized by one-step wet chemical method.By adjusting Rh^(Ⅲ)/Ni^(iⅡ)feed ratio,high-quality one-dimensional Rh_(1)Ni_(1)alloy nanodendrite assemblies(Rh_(1)Ni_(1)-NDs-As)can be synthesized selectively.Electrochemical measurements show that the introduction of Ni can enhance the electroactivity of Rh nanomaterials for methanol oxidation reaction(MOR)in alkaline media.For potential practical application,Rh_(1)Ni_(1)-NDs-As reveals improved electroactivity and durability for MOR compared to commercial Rh nanoparticle due to the particular morphology,Ni-doping,high electrochemical active area,and excellent anti-poison ability.Considering the facial synthesis and high electroactivity/durability,Rh_(1)Ni_(1)-NDs-As may be promising anode catalysts in direct methanol fuel cells.
基金the National Natural Science Foundation of China(No.51802205)the Australian Research Council and the Fundamental Research Funds for the Central Universities(No.YJ201789)。
文摘Rational design has been widely used to develop high-performance metal selenides-based electrode materials for supercapacitors.In this study,we develop a facile one-step solvothermal approach to synthesize binder-free Ni_(3)Se_(2) nanodendrite arrays grown on nickel foam as advanced positive electrodes for supercapacitors.Our Ni_(3)Se_(2) nanodendrite arrays on nickel foam exhibit a specific capacitance of 1234 Fg^(-1)(3.70 F cm^(-2))at a current density of 1 Ag^(-1) and a great rate capability,which is benefited from the excellent electrical conductivity and unique hierarchical nano-dendritic structure.Furthermore,an asymmetric supercapacitor device was assembled using activated carbon as the negative electrode and the Ni_(3)Se_(2) nanodendrite arrays on nickel foam as the positive electrode,obtaining a high energy density of 22.3 W h kg^(-1) at a power density of 160.4 W kg^(-1).
