Efficient charge separation is a key factor that determines the efficiency of photoelectrochemical(PEC)water splitting.Here,we introduce controllable vanadium dopants to the ZnO nanorod arrays(NRAs)as a photoanode.The...Efficient charge separation is a key factor that determines the efficiency of photoelectrochemical(PEC)water splitting.Here,we introduce controllable vanadium dopants to the ZnO nanorod arrays(NRAs)as a photoanode.The optimal vanadium doping amount exhibited a negative shift in the flatband potential,which was favorable for charge separation,resulting in a maximum applied bias photo-to-current efficiency of 0.8%,which was 2.1 times that of the pristine ZnO photoanode.More importantly,V-doping induced ZnO ferroelectric behavior was adopted to further optimize the PEC performance through the ferroelectric polarization by external electric field poling.The negative bias poling enlarged the band bending at the electrode/electrolyte interface,which facilitated the separation of photogenerated charges and thus resulted in an increased efficiency of 1.04%.This work provides a new method for the design of ferroelectric materials as efficient photoanodes for PEC water splitting.展开更多
Doping is critical for inducing ferroelectricity in hafnia films,yet the underlying mechanisms remain debated.Here,through first-principles studies,we elucidate the pivotal role played by the complex phase transition ...Doping is critical for inducing ferroelectricity in hafnia films,yet the underlying mechanisms remain debated.Here,through first-principles studies,we elucidate the pivotal role played by the complex phase transition mechanisms under carrier doping in understanding the origin of hafnia ferroelectricity.Specifically,electron doping orchestrates a metastable polar phase to stable antipolar phase transformation,driven by strong screening effects and weakened nonpolar covalent bonds,making n-type dopants rare.Conversely,weak screening effect and enhanced polar covalent bonding strengthen robust ferroelectricity,enabling significant ground-state phase transitions from the monoclinic to the polar orthorhombic phase and finally to the cubic phase under hole doping,a phenomenon prevalent in hafnia-based films doped with p-type dopants.Furthermore,this holeenhanced polar distortion also results in an inverse size effect in hafnia ferroelectric films,unlike perovskite ferroelectrics.Our findings offer new insights into the preparation of robust hafnia-based ferroelectric films through doping or interface engineering.展开更多
基金supported by the National Key Research and Development Program of China(No.2013CB932602)the National Key Research and Development Program of China 2016YFA0202701+3 种基金the Program of Introducing Talents of Discipline to Universities(B14003)National Natural Science Foundation of China(No.51527802,51232001,51372020 and 51602020)Beijing Municipal Science&Technology Commission(Z151100003315021)the China Postdoctoral Science Foundation(No.2016M600039).
文摘Efficient charge separation is a key factor that determines the efficiency of photoelectrochemical(PEC)water splitting.Here,we introduce controllable vanadium dopants to the ZnO nanorod arrays(NRAs)as a photoanode.The optimal vanadium doping amount exhibited a negative shift in the flatband potential,which was favorable for charge separation,resulting in a maximum applied bias photo-to-current efficiency of 0.8%,which was 2.1 times that of the pristine ZnO photoanode.More importantly,V-doping induced ZnO ferroelectric behavior was adopted to further optimize the PEC performance through the ferroelectric polarization by external electric field poling.The negative bias poling enlarged the band bending at the electrode/electrolyte interface,which facilitated the separation of photogenerated charges and thus resulted in an increased efficiency of 1.04%.This work provides a new method for the design of ferroelectric materials as efficient photoanodes for PEC water splitting.
基金supported by financial support from the National Natural Science Foundation of China(Grant Nos.92164108 and U23A20322,51971188,51471139)the National Key Research and Development Program of China(2023YFF0719600)+4 种基金Hunan Provincial Natural Science Foundation(Grant Nos.2023JJ50009 and 2023JJ30599)the Guangdong Provincial Key Laboratory Program from the Department of Science and Technology of Guangdong Province(2021B1212040001)the Outstanding Youth Science Foundation of Hunan Province,China(Grant No.2021JJ20041)the Key Project of Scientific Research Fund of Hunan Provincial Education Department(Grant No.23A0150)the Chongqing Municipal Education Commission Science and Technology Research Program Youth Project(KJQN202101423).
文摘Doping is critical for inducing ferroelectricity in hafnia films,yet the underlying mechanisms remain debated.Here,through first-principles studies,we elucidate the pivotal role played by the complex phase transition mechanisms under carrier doping in understanding the origin of hafnia ferroelectricity.Specifically,electron doping orchestrates a metastable polar phase to stable antipolar phase transformation,driven by strong screening effects and weakened nonpolar covalent bonds,making n-type dopants rare.Conversely,weak screening effect and enhanced polar covalent bonding strengthen robust ferroelectricity,enabling significant ground-state phase transitions from the monoclinic to the polar orthorhombic phase and finally to the cubic phase under hole doping,a phenomenon prevalent in hafnia-based films doped with p-type dopants.Furthermore,this holeenhanced polar distortion also results in an inverse size effect in hafnia ferroelectric films,unlike perovskite ferroelectrics.Our findings offer new insights into the preparation of robust hafnia-based ferroelectric films through doping or interface engineering.
