Construction of iridium(Ir)based active sites on certain acid stable supports now is a general strategy for the development of low-Ir OER catalysts.Atomically doped Ir in the lattice of acid stableγ-MnO_(2) has been ...Construction of iridium(Ir)based active sites on certain acid stable supports now is a general strategy for the development of low-Ir OER catalysts.Atomically doped Ir in the lattice of acid stableγ-MnO_(2) has been recently achieved,which shows high activity and stability though Ir usage was reduced more than 95%than that in current commercial proton exchange membrane water electrolyzer(PEMWE).However,the activity and stability enhancement by Ir doping inγ-MnO_(2) still remains elusive.Herein,high dispersion of iridium(up to 1.37 atom%)doping in the lattice ofγ-MnO_(2) has been achieved by optimizing the thermal decomposition of the iridium precursors.Benefiting from atomic dispersive doping of Ir,the optimized Ir-MnO_(2) catalyst shows high OER activity,as it has turnover frequency of 0.655 s^(–1) at an overpotential of 300 mV in 0.5 mol L^(-1) H_(2)SO_(4).The catalyst also shows high stability,as it can sustainably work at 100 mA cm^(-2) for 24 h.Experimental and theoretical studies reveal that Ir is preferentially doped intoβphase rather than R phase,and the Ir site is the active site for OER.The OER active site is postulated to be Ir^(5+)-O(H)-Mn^(3+)unit structure on the surface.Furthermore,Ir doping changes the potential determining step from the formation of O*to the formation of*OOH,emphasizing the promoting effect toward OER derived from Ir sites.This work not only demonstrates the possibility of achieving atomic-level doping of Ir on the surface of a support to dramatically reduce Ir usage,but also,more importantly,reveals the mechanism behind accounting for the stability and activity enhancement by Ir doping.These important findings may serve as valuable guidance for further development of more efficient,stable and cost-effective low Ir-based OER catalysts for PEMWE.展开更多
To improve the corrosion resistance of titanium(Ti)bipolar plate,titanium nitride(TiN)film was prepared on the surface of commercial TA1 pure titanium by magnetron reactive sputtering and pulse laser deposition(PLD)te...To improve the corrosion resistance of titanium(Ti)bipolar plate,titanium nitride(TiN)film was prepared on the surface of commercial TA1 pure titanium by magnetron reactive sputtering and pulse laser deposition(PLD)techniques,and the film prepared under different process parameters were evaluated.Results show that dense and complete TiN film can be obtained on TA1 surface under different preparation processes,and the corrosion current density of Ti substrate significantly increases.However,the composition of the film prepared by magnetron reactive sputtering is affected by the oxygen competition reaction,and its homogeneity is inferior to that of the film prepared by PLD.The comprehensive performance of the PLD-prepared film shows excellent characteristics in the terms of low corrosion current density(0.025μA·cm^(−2)),moderate corrosion overpotential(−0.106 V),and good hydrophobicity.展开更多
文摘Construction of iridium(Ir)based active sites on certain acid stable supports now is a general strategy for the development of low-Ir OER catalysts.Atomically doped Ir in the lattice of acid stableγ-MnO_(2) has been recently achieved,which shows high activity and stability though Ir usage was reduced more than 95%than that in current commercial proton exchange membrane water electrolyzer(PEMWE).However,the activity and stability enhancement by Ir doping inγ-MnO_(2) still remains elusive.Herein,high dispersion of iridium(up to 1.37 atom%)doping in the lattice ofγ-MnO_(2) has been achieved by optimizing the thermal decomposition of the iridium precursors.Benefiting from atomic dispersive doping of Ir,the optimized Ir-MnO_(2) catalyst shows high OER activity,as it has turnover frequency of 0.655 s^(–1) at an overpotential of 300 mV in 0.5 mol L^(-1) H_(2)SO_(4).The catalyst also shows high stability,as it can sustainably work at 100 mA cm^(-2) for 24 h.Experimental and theoretical studies reveal that Ir is preferentially doped intoβphase rather than R phase,and the Ir site is the active site for OER.The OER active site is postulated to be Ir^(5+)-O(H)-Mn^(3+)unit structure on the surface.Furthermore,Ir doping changes the potential determining step from the formation of O*to the formation of*OOH,emphasizing the promoting effect toward OER derived from Ir sites.This work not only demonstrates the possibility of achieving atomic-level doping of Ir on the surface of a support to dramatically reduce Ir usage,but also,more importantly,reveals the mechanism behind accounting for the stability and activity enhancement by Ir doping.These important findings may serve as valuable guidance for further development of more efficient,stable and cost-effective low Ir-based OER catalysts for PEMWE.
基金National Key Research and Development Program of China(2022YFB4002100)。
文摘To improve the corrosion resistance of titanium(Ti)bipolar plate,titanium nitride(TiN)film was prepared on the surface of commercial TA1 pure titanium by magnetron reactive sputtering and pulse laser deposition(PLD)techniques,and the film prepared under different process parameters were evaluated.Results show that dense and complete TiN film can be obtained on TA1 surface under different preparation processes,and the corrosion current density of Ti substrate significantly increases.However,the composition of the film prepared by magnetron reactive sputtering is affected by the oxygen competition reaction,and its homogeneity is inferior to that of the film prepared by PLD.The comprehensive performance of the PLD-prepared film shows excellent characteristics in the terms of low corrosion current density(0.025μA·cm^(−2)),moderate corrosion overpotential(−0.106 V),and good hydrophobicity.
