Xiuzhang Zheng,Aowei Sun,Yanling Qiu,Zixuan Wang,Jiangtao Xu,Jingquan Liu
Adjusting the electronic structure and intrinsic activity of the active site of the catalyst based on atomic implantation is the crucial to realizing efficient electrochemical water splitting in alkaline media. Thus, we introduce vanadium (V) atoms with abundant vacant d orbitals as dopants into nickel selenides (NiSe), which has abundant variable valence states, and successfully synthesise three-dimensional bi-functional catalysts self-supported on Ni foam (NF). The electron structure characterisation reveals that, compared with the pure NiSe phase, the oxidation states of Ni cations and electron concentration at the Se site in V–NiSe increase due to the V doping. These changes are accompanied by changes in the electronic structure and active sites in V–NiSe. The as-generated V–NiSe nanorods exhibit an optimised electronic structure, high number of active sites and highly rough nanorod array structure with large electrochemically active surface area and in situ growth characteristics of conductive NF. Thus, the as-generated V–NiSe nanorods catalysts exhibit excellent bi-functional catalytic activity, with 50 mA⋅cm −2 at an overpotential of 270.2 and 251.2 mV for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER), respectively, in KOH (1 M). Water electrolysis using V–NiSe as both the anode and cathode requires a cell voltage of 1.76 V to drive 50 mA⋅cm −2 , continuously operating for 80 h. This study provides a systematic understanding of the design of transition-metal catalysts using heteroatomic doping to control their electronic structure and catalytic activity.
Hui Zhang,Hui Han,Xuan Yang,Hongyu Ma,Zhifei Song,Xuqiang Ji
Active-site regeneration from d-band-center control engineering and electronic redistribution based on target-atom implantation is of enormous importance for efficient water oxidation. Here, low-activity Co catalytic sites of MgCo2O4 are reactivated for large-current (500 mA cm−2) and high-efficiency water oxidation through vanadium-atom electronic affinity synergy with Mg sites toward charge rearrangement around Co sites. Interestingly, very little vanadium (1.3 wt%) was implanted into MgCo2O4 to achieve atom-scale structure tailoring and electronic redistribution, reversing the Mg suppression effect on Co-site water oxidation of MgCo2O4. Vanadium-implantation-tailored MgCo2O4 coupled with MgO (V–MgCo2O4@MgO) exhibits significantly enhanced oxygen evolution reaction performance, with low overpotentials of 240 and 290 mV for 100 and 500 mA cm−2, respectively, in 1 M KOH. Operating at 500 mA cm−2, V–MgCo2O4@MgO has good catalytic stability for at least 20 hours. This work constructs excellent catalysts through atomic-level structural regulation and provides a new perspective for the principle of electronic-affinity synergy between V and Mg species toward Co–O bond optimization.
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