Sodium borohydride(NaBH_(4)) is considered as the most potential hydrogen storage material for portable proton exchange membrane fuel cells(PEMFC)because of its high theoretical hydrogen capacity.However,the slow and ...Sodium borohydride(NaBH_(4)) is considered as the most potential hydrogen storage material for portable proton exchange membrane fuel cells(PEMFC)because of its high theoretical hydrogen capacity.However,the slow and poor kinetic stability of hydrogen generation from NaBH_(4) hydrolysis limits its application.There are two main factors influencing the kinetics stability of hydrogen generation from NaBH_(4).One factor is that the alkaline byproducts(NaBO_(2)) of the hydrolysis reaction can increase the pH of the solution,thus inhibiting the reaction process.It mainly happens in the NaBH_(4) solution hydrolysis system.Another factor is that the monotonous increase in reaction temperature leads to uncontrollable and unpredictable hydrolysis rates in the solid NaBH_(4) hydrolysis system.This is due to the excess heat generated from this exothermic reaction in the initial reaction of NaBH_(4) hydrolysis.In this perspective,we summarize the latest research progress in hydrogen generation from NaBH_(4) and emphasize the design principles of catalysts for hydrogen generation from NaBH_(4) solution and solid state NaBH_(4).The importance of carbon as catalyst support material for NaBH_(4) hydrolysis is also highlighted.展开更多
Synthesizing polyol-based ester from biomass feedstocks for the preparation of biolubricant overcomes the dependence on petroleum oil usage.Albeit biomass-derived bio-oil is an alternative for the production of polyol...Synthesizing polyol-based ester from biomass feedstocks for the preparation of biolubricant overcomes the dependence on petroleum oil usage.Albeit biomass-derived bio-oil is an alternative for the production of polyol ester,upgrading is essential prior to use as biolubricant.Levulinic acid(LA),obtained from bio-oil was applied for the catalytic esterification with two polyols,e.g.,trimethylolpropane(TMP)and pentaerythritol(PE),in the presence of mixed-ligand Ni(Ⅱ),Co(Ⅱ),and Fe(Ⅱ)complexes as catalyst.New mixed-ligand coordination complexes with empirical formula;[Ni(Phe)(Bpy)Cl].H2O,[Co(Phe)(Bpy)Cl].H2O,and[Fe(Phe)(Tyr)Cl].H2O were synthesized by the reaction of ligands[L-phenylalanine(Phe),4,4'-bipyridine(Bpy),and L-tyrosine(Tyr)]with metal chloride salts and characterized by elemental analysis,magnetic susceptibility,FTIR,TGA/DTA,powder-XRD,and SEM techniques.This study aims to investigate the catalytic activities of the complexes via esterification reaction of levulinic acid with trimethylolpropane and pentaerythritol.In addition,these catalysts were further employed for the in situ hydrogenation of levulinate esters via NaBH_(4) at room temperature upon refluxing.Indeed,the iron(Ⅱ)complex was more potential,exhibiting its efficiency as a homogeneous catalyst for esterification-hydrogenation reaction for synthesizing ester-based oils.展开更多
We present theoretical studies for second-and third-order elastic constants in NaBH_(4) based on ab initio calculations.Our calculated second−order elastic constants agree well with available experimental results.The ...We present theoretical studies for second-and third-order elastic constants in NaBH_(4) based on ab initio calculations.Our calculated second−order elastic constants agree well with available experimental results.The anharmonic properties of NaBH_(4),such as pressure derivative of the second−order elastic constants and the Grüneisen constants for long-wavelength acoustic mode γ(q,j),are characterized using the third-order elastic constants.展开更多
Homogeneous NaBH_(4)-reduced Co_(O)_(4) thin film electrodes with enhanced oxygen evolution electrocatalysis were obtained via a controlled-synthesis route.Firstly CoOx colloids were synthesized via ethylene glycol so...Homogeneous NaBH_(4)-reduced Co_(O)_(4) thin film electrodes with enhanced oxygen evolution electrocatalysis were obtained via a controlled-synthesis route.Firstly CoOx colloids were synthesized via ethylene glycol solvothermal method and cast on conductive glass substrates.The oxygen evolution reaction(OER) electrocatalysis of these asprepared CO_(3)O_(4) thin films were then significantly enhanced via a simple surface reduction by NaBH_(4) solution.The OER catalytic performance of the NaBH_(4)-reduced thin films was strongly dependent on the NaBH_(4) concentration.The use of NaBH_(4)-reduced thin film electrodes for OER in alkaline solution supported higher current density and consequently negative shifts of the onset potential compared to that of the pristine.The optimal B_(12.5,20)-CO_(3)O_(4) thin films exhibited excellent OER catalytic performances:At the current density of 10 mA·cm^(-2),a low overpotential of 365 mV and a small Tafel slope of 59.0 mV·dec^(-1) were observed.In addition,these B_(12.5,20)-CO_(3)O_(4) thin film electrodes possessed good stability that can well recover its OER performance in a 24-h chronoamperometric stability test.展开更多
Application of transition metal boride(TMB) catalysts towards hydrolysis of NaBH_(4) holds great significance to help relieve the energy crisis. Herein, we present a facile and versatile metal-organic framework(MOF) a...Application of transition metal boride(TMB) catalysts towards hydrolysis of NaBH_(4) holds great significance to help relieve the energy crisis. Herein, we present a facile and versatile metal-organic framework(MOF) assisted strategy to prepare Co_(2)B-CoPO_x with massive boron vacancies by introducing phytic acid(PA) cross-linked Co complexes that are acquired from reaction of PA and ZIF-67 into cobalt boride. The PA etching effectively breaks down the structure of ZIF-67 to create more vacancies, favoring the maximal exposure of active sites and elevation of catalytic activity. Experimental results demonstrate a drastic electronic interaction between Co and the dopant phosphorous(P), thereby the robustly electronegative P induces electron redistribution around the metal species, which facilitates the dissociation of B-H bond and the adsorption of H_(2)O molecules. The vacancy-rich Co_(2)B-CoPO_x catalyst exhibits scalable performance, characterized by a high hydrogen generation rate(HGR) of 7716.7 m L min^(-1)g^(-1) and a low activation energy(Ea) of 44.9 k J/mol, rivaling state-of-the-art catalysts. This work provides valuable insights for the development of advanced catalysts through P doping and boron vacancy engineering and the design of efficient and sustainable energy conversion systems.展开更多
基金supported by MOST of China(No.2021YFB4000603)NSFC(No.22179002 and 51971004).
文摘Sodium borohydride(NaBH_(4)) is considered as the most potential hydrogen storage material for portable proton exchange membrane fuel cells(PEMFC)because of its high theoretical hydrogen capacity.However,the slow and poor kinetic stability of hydrogen generation from NaBH_(4) hydrolysis limits its application.There are two main factors influencing the kinetics stability of hydrogen generation from NaBH_(4).One factor is that the alkaline byproducts(NaBO_(2)) of the hydrolysis reaction can increase the pH of the solution,thus inhibiting the reaction process.It mainly happens in the NaBH_(4) solution hydrolysis system.Another factor is that the monotonous increase in reaction temperature leads to uncontrollable and unpredictable hydrolysis rates in the solid NaBH_(4) hydrolysis system.This is due to the excess heat generated from this exothermic reaction in the initial reaction of NaBH_(4) hydrolysis.In this perspective,we summarize the latest research progress in hydrogen generation from NaBH_(4) and emphasize the design principles of catalysts for hydrogen generation from NaBH_(4) solution and solid state NaBH_(4).The importance of carbon as catalyst support material for NaBH_(4) hydrolysis is also highlighted.
基金financial support from Universiti Malaya(Grand Challenge(Innovative Technology(ITRC)(GC001B-14AET)),RU Geran(ST012-2018)Postgraduate(Research Grant(PPP,Project number:PG250-2016A)).
文摘Synthesizing polyol-based ester from biomass feedstocks for the preparation of biolubricant overcomes the dependence on petroleum oil usage.Albeit biomass-derived bio-oil is an alternative for the production of polyol ester,upgrading is essential prior to use as biolubricant.Levulinic acid(LA),obtained from bio-oil was applied for the catalytic esterification with two polyols,e.g.,trimethylolpropane(TMP)and pentaerythritol(PE),in the presence of mixed-ligand Ni(Ⅱ),Co(Ⅱ),and Fe(Ⅱ)complexes as catalyst.New mixed-ligand coordination complexes with empirical formula;[Ni(Phe)(Bpy)Cl].H2O,[Co(Phe)(Bpy)Cl].H2O,and[Fe(Phe)(Tyr)Cl].H2O were synthesized by the reaction of ligands[L-phenylalanine(Phe),4,4'-bipyridine(Bpy),and L-tyrosine(Tyr)]with metal chloride salts and characterized by elemental analysis,magnetic susceptibility,FTIR,TGA/DTA,powder-XRD,and SEM techniques.This study aims to investigate the catalytic activities of the complexes via esterification reaction of levulinic acid with trimethylolpropane and pentaerythritol.In addition,these catalysts were further employed for the in situ hydrogenation of levulinate esters via NaBH_(4) at room temperature upon refluxing.Indeed,the iron(Ⅱ)complex was more potential,exhibiting its efficiency as a homogeneous catalyst for esterification-hydrogenation reaction for synthesizing ester-based oils.
基金by the National Natural Science Foundation of China under Grants Nos 10647008,10674028,50971099the Department of Education of Shaanxi Province of China under Grant No.09JK752.
文摘We present theoretical studies for second-and third-order elastic constants in NaBH_(4) based on ab initio calculations.Our calculated second−order elastic constants agree well with available experimental results.The anharmonic properties of NaBH_(4),such as pressure derivative of the second−order elastic constants and the Grüneisen constants for long-wavelength acoustic mode γ(q,j),are characterized using the third-order elastic constants.
基金supported by National Key Research and Development Program of China (2016YFB0600503, 2016YFC0400503, 2016YFC0400506)。
文摘Homogeneous NaBH_(4)-reduced Co_(O)_(4) thin film electrodes with enhanced oxygen evolution electrocatalysis were obtained via a controlled-synthesis route.Firstly CoOx colloids were synthesized via ethylene glycol solvothermal method and cast on conductive glass substrates.The oxygen evolution reaction(OER) electrocatalysis of these asprepared CO_(3)O_(4) thin films were then significantly enhanced via a simple surface reduction by NaBH_(4) solution.The OER catalytic performance of the NaBH_(4)-reduced thin films was strongly dependent on the NaBH_(4) concentration.The use of NaBH_(4)-reduced thin film electrodes for OER in alkaline solution supported higher current density and consequently negative shifts of the onset potential compared to that of the pristine.The optimal B_(12.5,20)-CO_(3)O_(4) thin films exhibited excellent OER catalytic performances:At the current density of 10 mA·cm^(-2),a low overpotential of 365 mV and a small Tafel slope of 59.0 mV·dec^(-1) were observed.In addition,these B_(12.5,20)-CO_(3)O_(4) thin film electrodes possessed good stability that can well recover its OER performance in a 24-h chronoamperometric stability test.
基金supported by the National Natural Science Foundation of China (No.21965005)Natural Science Foundation of Guangxi Province (No.2021GXNSFAA076001)+1 种基金Guangxi Technology Base and Talent Subject (Nos.GUIKE AD18126001, GUIKE AD20297039)Innovation Project of Guangxi Graduate Education (Nos.YCSW2023140, YCBZ2023062)。
文摘Application of transition metal boride(TMB) catalysts towards hydrolysis of NaBH_(4) holds great significance to help relieve the energy crisis. Herein, we present a facile and versatile metal-organic framework(MOF) assisted strategy to prepare Co_(2)B-CoPO_x with massive boron vacancies by introducing phytic acid(PA) cross-linked Co complexes that are acquired from reaction of PA and ZIF-67 into cobalt boride. The PA etching effectively breaks down the structure of ZIF-67 to create more vacancies, favoring the maximal exposure of active sites and elevation of catalytic activity. Experimental results demonstrate a drastic electronic interaction between Co and the dopant phosphorous(P), thereby the robustly electronegative P induces electron redistribution around the metal species, which facilitates the dissociation of B-H bond and the adsorption of H_(2)O molecules. The vacancy-rich Co_(2)B-CoPO_x catalyst exhibits scalable performance, characterized by a high hydrogen generation rate(HGR) of 7716.7 m L min^(-1)g^(-1) and a low activation energy(Ea) of 44.9 k J/mol, rivaling state-of-the-art catalysts. This work provides valuable insights for the development of advanced catalysts through P doping and boron vacancy engineering and the design of efficient and sustainable energy conversion systems.
