CoAl-LDH/CoFe基普鲁士蓝衍生双金属磷化物异质结构的高效电催化OER性能

Efficient Electrocatalytic OER Performance of CoAl LDH/CoFe-Based Prussian Blue-Derived Bimetallic Phosphide Heterostructures

摘要:

电催化水解是生产绿氢的有效途径，但是其阳极的氧气析出反应（OER）动力学缓慢，限制了其大规模应用。采用液相回流法制备了超薄的CoAl-LDH十二边形纳米片，其大的表面积成为良好的催化剂载体，且表面大量未饱和的Co²⁺可有效配位其他阴离子。结合共沉淀法和离子交换法，在CoAl-LDH纳米片表面组装大量超小的CoFe-PB纳米颗粒，以形成CoAl-LDH/CoFe-PB异质结构，再通过原位磷化策略获得CoAlP/CoFeP_x@NC异质结构。在磷化过程中，CoFe-PB纳米颗粒会转化为氮掺杂的碳包裹的CoFeP_x核壳纳米颗粒，以提供足够的活性位点，同时他们也牢固地负载在CoAl-LDH转化而成的CoAlP纳米片的表面，形成稳定的异质结构。由于CoAlP/CoFeP_x@NC异质结构具有丰富的组分、独特的多孔结构和稳定的片层结构，其可以获得优异的电催化OER活性。在碱性电解液（1 mol?L^-1的KOH）中，CoAlP/CoFeP_x@NC在电流密度为10 mA?cm^-2下的过电位为334 mV（vs. RHE）。该研究为低成本和稳定高效的多元金属磷化物基异质结构的电催化剂的设计与制备提供了思路。

Abstract:

Electrochemical water splitting is an effective way to produce green hydrogen， but the sluggish kinetics of the anodic oxygen evolution reaction （OER） limits its large-scale application. In this paper， ultrathin CoAl-LDH dodecagonal nanosheets were first prepared using the liquid reflux method. The large surface area of these nanosheets makes them a good catalyst support， and the large amount of unsaturated Co²⁺ on the surface can effectively coordinate other anions. Co-precipitation and ion exchange methods were then integrated to assemble a large number of ultra-small CoFe-PB nanoparticles on the surface of CoAl-LDH nanosheets， forming a CoAl-LDH/CoFe-PB heterostructure. Finally， the CoAlP/CoFeP_x@NC heterostructure was obtained through an in situ phosphating strategy. During the phosphating process， the CoFe-PB nanoparticles are transformed into nitrogen-doped carbon-wrapped CoFeP_x core-shell nanoparticles to provide sufficient active sites. At the same time， CoFeP_x is firmly loaded onto the surface of CoAlP nanosheets that were converted from CoAl-LDH， forming a stable heterostructure. With the help of abundant components， unique porous structure， and stable lamellar structure， the CoAlP/CoFeP_x@NC heterostructure can obtain excellent electrocatalytic OER activity. In an alkaline electrolyte （1 mol·L^-1 KOH）， the overpotential of CoAlP/CoFeP_x@NC at a current density of 10 mA·cm^-2 is 334 mV （vs. RHE）. This study provides ideas for the design and preparation of low-cost， stable and efficient multi-metal phosphide-based heterostructure electrocatalysts.