Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enh...Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.展开更多
Estimation of leaf chlorophyll content(LCC) by proximal sensing is an important tool for photosynthesis evaluation in high-throughput phenotyping. The temporal variability of crop biochemical properties and canopy str...Estimation of leaf chlorophyll content(LCC) by proximal sensing is an important tool for photosynthesis evaluation in high-throughput phenotyping. The temporal variability of crop biochemical properties and canopy structure across different growth stages has great impacts on wheat LCC estimation, known as growth stage effects. It will result in the heterogeneity of crop canopy at different growth stages, which would mask subtle spectral response of biochemistry variations. This study aims to explore spectral responses on the growth stage effects and establish LCC models suited for different growth stages. A total number of 864 pairwise samples of wheat canopy spectra and LCC values with 216 observations of each stage were sampled at the tillering, jointing, booting and heading stages in 2021. Firstly, statistical analysis of LCC and spectral response presented different distribution traits and typical spectral variations peak at 470, 520 and 680 nm. Correlation analysis between LCC and reflectance showed typical red edge shifts. Secondly, the testing model of partial least square(PLS) established by the entire datasets to validate the predictive performance at each stage yielded poor LCC estimation accuracy. The spectral wavelengths of red edge(RE) and blue edge(BE) shifts and the poor estimation capability motivated us to further explore the growth stage effects by establishing LCC models at respective growth periods.Finally, competitive adaptive reweighted sampling PLS(CARS-PLS), decision tree(DT) and random forest(RF) were used to select sensitive bands and establish LCC models at specific stages. Bayes optimisation was used to tune the hyperparameters of DT and RF regression. The modelling results indicated that CARS-PLS and DT did not extract specific wavelengths that could decrease the influences of growth stage effects. From the RF out-of-bag(OOB) evaluation, the sensitive wavelengths displayed consistent spectral shifts from BE to GP and from RE to RV from tillering to heading stages. Compared with CARS-PLS and DT,results of RF modelling yielded an estimation accuracy with deviation to performance(RPD) of 2.11, 2.02,3.21 and 3.02, which can accommodate the growth stage effects. Thus, this study explores spectral response on growth stage effects and provides models for chlorophyll content estimation to satisfy the requirement of high-throughput phenotyping.展开更多
Nickel(Ni)-based materials act as one of the most promising candidates as platinum-group-metal-free(PGM-free)electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline solution.Nevertheless,the electrocatalytic ...Nickel(Ni)-based materials act as one of the most promising candidates as platinum-group-metal-free(PGM-free)electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline solution.Nevertheless,the electrocatalytic activity of pure Ni is significantly limited due to the sluggish kinetics under alkaline condition.To accelerate the kinetics,constructing heterostructures and nitride structures have been developed as two representative strategies.Here,we combined the two methods and presented a facile synthesis of the sheet-like Ni_(3)N/MoO_(2)in-plane heterostructures for enhanced HOR in alkaline electrolytes.Relative to Ni or Ni_(3)N,the Ni_(3)N/MoO_(2)in-plane heterostructures exhibited a significantly increased mass activity by 8.6-fold or 4.4-fold,respectively.Mechanistic studies revealed that the enhanced activity of Ni_(3)N/MoO_(2)could be attributed to the weakened hydrogen adsorption and strengthened hydroxyl adsorption.This work provides a facile approach to design high-efficiency catalysts for hydrogen-oxidation catalysis and beyond.展开更多
Controlling the particle size of catalyst to understand the active sites is the key to design efficient electrocatalysts toward hydrogen electrode reactions including hydrogen oxidation and evolution(HOR/HER).Herein, ...Controlling the particle size of catalyst to understand the active sites is the key to design efficient electrocatalysts toward hydrogen electrode reactions including hydrogen oxidation and evolution(HOR/HER).Herein, the hydrogen and hydroxyl adsorption on Ru/C could be effectively tuned for HOR/HER by simple controlling the particle sizes. It is found that the metallic Ru(Ru0) is the active site for HOR/HER, while oxidized Ru(Rux+) will hinder the adsorption and desorption of hydrogen on the catalyst. For the HOR,catalyst with small particles is more efficient, due to it is a three-phase interface reaction of gas on the surface of the catalyst. For the HER, the metallic state of Ru is crucial. The deconvolution of hydrogen peaks indicates that the catalytic sites with low hydrogen binding energy(HBE) shoulder the majority of the HOR activity. CO stripping curve further demonstrates that the stronger hydroxyl species(OHad)affinity is beneficial to promote the HOR performance. The results indicate that the design of efficient HOR/HER catalyst should focus on the balance between particle size and metallic states.展开更多
Diamond-like carbon(DLC)films are deposited on rubber surfaces to protect the rubber components,and surface pretreatment of the rubber substrates prior to the film deposition can improve the adhesion between the DLC f...Diamond-like carbon(DLC)films are deposited on rubber surfaces to protect the rubber components,and surface pretreatment of the rubber substrates prior to the film deposition can improve the adhesion between the DLC films and the rubber.Thus,the principal purpose of this work concentrates on determining the effects of argon(Ar),oxygen(O_(2)),nitrogen(N_(2)),and hydrogen(H_(2))plasma pretreatments on the adhesion and friction performance of the DLC films deposited on rubber(DLC/rubber).The results indicated that the Ar plasma pretreatment promoted the formation of a compact layer on the rubber surface.By contrast,massive fillers were exposed on the rubber surface after oxygen or nitrogen plasma pretreatments.Moreover,the typical micrometer-scale patches divided by random cracks were observed on the surface of DLC/rubber,except for the sample pretreated with oxygen plasma.The adhesion of DLC/rubber was found to strengthen with the removal of weak boundary layers and the generation of free radicals on the rubber surface after plasma pretreatment.The tribo-tests revealed that DLC/rubber with O_(2),N_(2),and H_(2) plasma pretreatments cannot achieve optimal friction performance.Significantly,DLC/rubber with Ar plasma pretreatment exhibited a low and stable friction coefficient of 0.19 and superior wear resistance,which was correlated to the high adhesion,good load-bearing of the rubber surface,and the approximate sine function of the surface profile of the DLC film.展开更多
基金financially supported by the National Natural Science Foundation of China(22279036)the Innovation Talent Recruitment Base of New Energy Chemistry Device(B21003)the Fundamental Research Funds for the Central Universities(no.2019kfyRCPY100).
文摘Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.
基金supported by the National Key Research and Development Program (2019YFE0125500)University-Locality Integrative Development Project of Yantai (2020XDRHXMPT35)+1 种基金the National Natural Science Foundation of China (31971785 and41801245)the Graduate Training Project of China Agricultural University (JG2019004, JG202026, YW2020007, QYJC202101, and JG202102)。
文摘Estimation of leaf chlorophyll content(LCC) by proximal sensing is an important tool for photosynthesis evaluation in high-throughput phenotyping. The temporal variability of crop biochemical properties and canopy structure across different growth stages has great impacts on wheat LCC estimation, known as growth stage effects. It will result in the heterogeneity of crop canopy at different growth stages, which would mask subtle spectral response of biochemistry variations. This study aims to explore spectral responses on the growth stage effects and establish LCC models suited for different growth stages. A total number of 864 pairwise samples of wheat canopy spectra and LCC values with 216 observations of each stage were sampled at the tillering, jointing, booting and heading stages in 2021. Firstly, statistical analysis of LCC and spectral response presented different distribution traits and typical spectral variations peak at 470, 520 and 680 nm. Correlation analysis between LCC and reflectance showed typical red edge shifts. Secondly, the testing model of partial least square(PLS) established by the entire datasets to validate the predictive performance at each stage yielded poor LCC estimation accuracy. The spectral wavelengths of red edge(RE) and blue edge(BE) shifts and the poor estimation capability motivated us to further explore the growth stage effects by establishing LCC models at respective growth periods.Finally, competitive adaptive reweighted sampling PLS(CARS-PLS), decision tree(DT) and random forest(RF) were used to select sensitive bands and establish LCC models at specific stages. Bayes optimisation was used to tune the hyperparameters of DT and RF regression. The modelling results indicated that CARS-PLS and DT did not extract specific wavelengths that could decrease the influences of growth stage effects. From the RF out-of-bag(OOB) evaluation, the sensitive wavelengths displayed consistent spectral shifts from BE to GP and from RE to RV from tillering to heading stages. Compared with CARS-PLS and DT,results of RF modelling yielded an estimation accuracy with deviation to performance(RPD) of 2.11, 2.02,3.21 and 3.02, which can accommodate the growth stage effects. Thus, this study explores spectral response on growth stage effects and provides models for chlorophyll content estimation to satisfy the requirement of high-throughput phenotyping.
文摘Nickel(Ni)-based materials act as one of the most promising candidates as platinum-group-metal-free(PGM-free)electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline solution.Nevertheless,the electrocatalytic activity of pure Ni is significantly limited due to the sluggish kinetics under alkaline condition.To accelerate the kinetics,constructing heterostructures and nitride structures have been developed as two representative strategies.Here,we combined the two methods and presented a facile synthesis of the sheet-like Ni_(3)N/MoO_(2)in-plane heterostructures for enhanced HOR in alkaline electrolytes.Relative to Ni or Ni_(3)N,the Ni_(3)N/MoO_(2)in-plane heterostructures exhibited a significantly increased mass activity by 8.6-fold or 4.4-fold,respectively.Mechanistic studies revealed that the enhanced activity of Ni_(3)N/MoO_(2)could be attributed to the weakened hydrogen adsorption and strengthened hydroxyl adsorption.This work provides a facile approach to design high-efficiency catalysts for hydrogen-oxidation catalysis and beyond.
基金supported by the National Natural Science Foundation (No. 91963109)。
文摘Controlling the particle size of catalyst to understand the active sites is the key to design efficient electrocatalysts toward hydrogen electrode reactions including hydrogen oxidation and evolution(HOR/HER).Herein, the hydrogen and hydroxyl adsorption on Ru/C could be effectively tuned for HOR/HER by simple controlling the particle sizes. It is found that the metallic Ru(Ru0) is the active site for HOR/HER, while oxidized Ru(Rux+) will hinder the adsorption and desorption of hydrogen on the catalyst. For the HOR,catalyst with small particles is more efficient, due to it is a three-phase interface reaction of gas on the surface of the catalyst. For the HER, the metallic state of Ru is crucial. The deconvolution of hydrogen peaks indicates that the catalytic sites with low hydrogen binding energy(HBE) shoulder the majority of the HOR activity. CO stripping curve further demonstrates that the stronger hydroxyl species(OHad)affinity is beneficial to promote the HOR performance. The results indicate that the design of efficient HOR/HER catalyst should focus on the balance between particle size and metallic states.
基金carried out in Youth Innovation Promotion Association CAS(No.2017459)the National Natural Science Foundation of China(Nos.U1737213 and 51911530114).
文摘Diamond-like carbon(DLC)films are deposited on rubber surfaces to protect the rubber components,and surface pretreatment of the rubber substrates prior to the film deposition can improve the adhesion between the DLC films and the rubber.Thus,the principal purpose of this work concentrates on determining the effects of argon(Ar),oxygen(O_(2)),nitrogen(N_(2)),and hydrogen(H_(2))plasma pretreatments on the adhesion and friction performance of the DLC films deposited on rubber(DLC/rubber).The results indicated that the Ar plasma pretreatment promoted the formation of a compact layer on the rubber surface.By contrast,massive fillers were exposed on the rubber surface after oxygen or nitrogen plasma pretreatments.Moreover,the typical micrometer-scale patches divided by random cracks were observed on the surface of DLC/rubber,except for the sample pretreated with oxygen plasma.The adhesion of DLC/rubber was found to strengthen with the removal of weak boundary layers and the generation of free radicals on the rubber surface after plasma pretreatment.The tribo-tests revealed that DLC/rubber with O_(2),N_(2),and H_(2) plasma pretreatments cannot achieve optimal friction performance.Significantly,DLC/rubber with Ar plasma pretreatment exhibited a low and stable friction coefficient of 0.19 and superior wear resistance,which was correlated to the high adhesion,good load-bearing of the rubber surface,and the approximate sine function of the surface profile of the DLC film.
