磷化镍电催化氧析出活性的来源:原位电化学氧化和Cr掺杂实现高催化性能

Origin of the electrocatalytic oxygen evolution activity of nickel phosphides: in-situ electrochemical oxidation and Cr doping to achieve high performance

锌-空气电池(ZnABs)因其高理论能量密度和环境友好的优势而被认为是下一代电子产品的理想能源器件.然而,由于缺乏高效且经济适用的电催化剂,限制了其广泛应用.过渡金属磷化物(TMP)因其独特的物理化学性质而被认为是最有前途的催化剂.因此,本文采用表面工程和设计多金属位点的策略,设计合成了(Ni_(1-x)Cr_(x))_(2)P(0≤x≤0.15)材料.研究发现,该材料在氧析出反应(OER)的初始阶段甚至催化剂的活化过程就已发生了原位电化学氧化,最终转变为具有高效OER活性的Cr-NiOOH.通过密度泛函理论(DFT)计算并结合实验表征,揭示了表面工程、多金属活性中心和原位相变能够协同调谐催化剂的电子结构,从而显著地提升OER催化性能.当将(Ni_(0.90)Cr_(0.10))2P组装成可充电ZnAB时,其可在5 m A cm^(-2)的电流密度下稳定循环208 h且循环时过电位无明显变化.当被应用于柔性固态ZnAB时,该电池可以高效且平稳地为可穿戴电子设备供电.

Zinc-air batteries(ZnABs) with high theoretical capacity and environmental benignity are the most promising candidates for next-generation electronics. However, their large-scale applications are greatly hindered due to the lack of high-efficient and cost-effective electrocatalysts. Transition metal phosphides(TMPs) have been reported as promising electrocatalysts. Notably,(Ni_(1-x)Cr_(x))_(2) P(0≤x≤0.15) is an unstable electrocatalyst, which undergoes in-situ electrochemical oxidation during the initial oxygen evolution reaction(OER) and even in the activation cycles, and is eventually converted to Cr-NiOOH serving as the actual OER active sites with high efficiency. Density functional theory(DFT) simulations and experimental results elucidate that the OER performance could be significantly promoted by the synergistic effect of surface engineering and electronic modulations by Cr doping and in-situ phase transformation. The constructed rechargeable ZnABs could stably cycle for more than 208 h at 5 m A cm^(-2), while the voltage degradation is negligible. Furthermore, the developed catalytic materials could be assembled into flexible and all-solid-state Zn ABs to power wearable electronics with high performance.