Developing low-cost but efficient hydrogen evolution reaction(HER)electrocatalysts over whole pH values is a significant but daunting task for the large-scale application of electrochemical hydrogen production.Herein,...Developing low-cost but efficient hydrogen evolution reaction(HER)electrocatalysts over whole pH values is a significant but daunting task for the large-scale application of electrochemical hydrogen production.Herein,we develop,for the first time,a scalable MOF-assisted strategy for the fabrication and microstructural optimization of multi-shelled hollow N-doped carbon nanosheet arrays with confined Co/CoP heterostructures on carbon cloth(Co/CoP@NC/CC)for boosting HER performances.The key to this strategy is the step-by-step epitaxial growth of unprecedented multilayer ZIF-L arrays on carbon cloth,which are subsequently pyrolyzed and controllably phosphorized to achieve the precise control over the shell number and nanoarchitectures of the Co/CoP@NC/CC.Impressively,the HER performances can be significantly enhanced by increasing hollow shell number,and the optimal triple-shelled hollow Co/CoP@NC/CC exhibits low overpotentials of 86,78 and 145 mV in acidic,alkaline and neutral media to deliver a current density of 10 mA cm^(-2),respectively,ranking as one of the best Co-based HER electrocatalysts over whole pH values.Further DFT calculations suggest that the Co/CoP heterostructures can effectively boost the cleavage of H–OH to generate protons and optimize the adsorption energy of hydrogen(ΔG_(H*)),which,together with the large electrode/electrolyte interface and accelerated charge/mass transfer of multi-shelled hollow array structure as well as the good conductivity and dispersity,are responsible for the remarkably improved HER performances.This study not only provides a new toolbox for enriching the family of multi-shelled nanoarchitecture materials,but also points out a general and effective route to develop highly efficient self-supported electrode materials for energy-related applications and beyond.展开更多
Zeolitic imidazolate frameworks(ZIFs)are an important subclass of metal-organic frameworks(MOFs)with zeolite-type topology,which can be fabricated under ambient synthesis conditions.However,the applications of ZIFs ar...Zeolitic imidazolate frameworks(ZIFs)are an important subclass of metal-organic frameworks(MOFs)with zeolite-type topology,which can be fabricated under ambient synthesis conditions.However,the applications of ZIFs are commonly limited due to the weak hydrostability of their metal–ligand coordination bonds,particularly under humid and aqueous conditions.In this work,as an example,the hydrolysis behaviours of ZIF-L with a special focus on ZIF-L coatings were tested at aqueous conditions with a wide range of pHs to systematically study and fundamentally understand their structural stability and degradation mechanism.Pristine ZIF-L powder and ZIF-L coatings were severely damaged after only 24 h in aqueous media.Interestingly,the ZIF-L coatings showed two distinct hydrolyzation pathways regardless of pH conditions,exhibiting either a ring-shaped etching or unfolding behaviours.While the ZIF-L powders were hydrolyzed almost identically across all pH conditions.With this new understanding,a facile silk fibroin(SF)protein modification method was developed to enhance the hydrostability of ZIF-L coatings in aqueous media.The effect of protein concentration on surface coating was systemically studied.ZIF-L coating retained its surface morphology after soaking in water and demonstrated switchable super wetting properties and superior separation performance for oil/water mixture.As a result,the quick SF protein modification significantly enhanced the stability of ZIF-L coatings under various pHs,while retaining their switchable wetting property and excellent separation performance.展开更多
基金financially supported from the National Natural Science Foundation of China (21825802)Guangdong Natural Science Funds for Distinguished Young Scholar (2018B030306050)the Natural Science Foundation of Guangdong Province (2017A030312005)。
文摘Developing low-cost but efficient hydrogen evolution reaction(HER)electrocatalysts over whole pH values is a significant but daunting task for the large-scale application of electrochemical hydrogen production.Herein,we develop,for the first time,a scalable MOF-assisted strategy for the fabrication and microstructural optimization of multi-shelled hollow N-doped carbon nanosheet arrays with confined Co/CoP heterostructures on carbon cloth(Co/CoP@NC/CC)for boosting HER performances.The key to this strategy is the step-by-step epitaxial growth of unprecedented multilayer ZIF-L arrays on carbon cloth,which are subsequently pyrolyzed and controllably phosphorized to achieve the precise control over the shell number and nanoarchitectures of the Co/CoP@NC/CC.Impressively,the HER performances can be significantly enhanced by increasing hollow shell number,and the optimal triple-shelled hollow Co/CoP@NC/CC exhibits low overpotentials of 86,78 and 145 mV in acidic,alkaline and neutral media to deliver a current density of 10 mA cm^(-2),respectively,ranking as one of the best Co-based HER electrocatalysts over whole pH values.Further DFT calculations suggest that the Co/CoP heterostructures can effectively boost the cleavage of H–OH to generate protons and optimize the adsorption energy of hydrogen(ΔG_(H*)),which,together with the large electrode/electrolyte interface and accelerated charge/mass transfer of multi-shelled hollow array structure as well as the good conductivity and dispersity,are responsible for the remarkably improved HER performances.This study not only provides a new toolbox for enriching the family of multi-shelled nanoarchitecture materials,but also points out a general and effective route to develop highly efficient self-supported electrode materials for energy-related applications and beyond.
基金supported by start-up funding from the School of Engineering,at the University of Edinburgh.
文摘Zeolitic imidazolate frameworks(ZIFs)are an important subclass of metal-organic frameworks(MOFs)with zeolite-type topology,which can be fabricated under ambient synthesis conditions.However,the applications of ZIFs are commonly limited due to the weak hydrostability of their metal–ligand coordination bonds,particularly under humid and aqueous conditions.In this work,as an example,the hydrolysis behaviours of ZIF-L with a special focus on ZIF-L coatings were tested at aqueous conditions with a wide range of pHs to systematically study and fundamentally understand their structural stability and degradation mechanism.Pristine ZIF-L powder and ZIF-L coatings were severely damaged after only 24 h in aqueous media.Interestingly,the ZIF-L coatings showed two distinct hydrolyzation pathways regardless of pH conditions,exhibiting either a ring-shaped etching or unfolding behaviours.While the ZIF-L powders were hydrolyzed almost identically across all pH conditions.With this new understanding,a facile silk fibroin(SF)protein modification method was developed to enhance the hydrostability of ZIF-L coatings in aqueous media.The effect of protein concentration on surface coating was systemically studied.ZIF-L coating retained its surface morphology after soaking in water and demonstrated switchable super wetting properties and superior separation performance for oil/water mixture.As a result,the quick SF protein modification significantly enhanced the stability of ZIF-L coatings under various pHs,while retaining their switchable wetting property and excellent separation performance.
