Superassembly of NiCoOx solid solution hybrids with a 2D/3D porous polyhedron-on-sheet structure for multi-functional electrocatalytic oxidation

Abstract

The preparation of highly active electrocatalysts with good stability is very important for environmental pollution treatment and organic oxidation. Herein, we highlight an advanced multi-functional electrocatalyst based on NiCoO_x solid solution hybrids with a hierarchical architecture and high porosity. The 2D nanosheets grafted with 3D polyhedrons possess a large specific surface area, higher ratio of surface area-to-volume, more edge active sites and excellent structural stability to boost catalytic activities. The high porosity can provide more active sites and ensure ion permeation channels for facile mass transport. The close contact between (Ni, Co)O and (Ni, Co)₃O₄ allows facile charge transport, contributing to favorable reaction kinetics with the synergy of phase engineering between (Ni, Co)O and (Ni, Co)₃O₄. Importantly, DFT calculations have proved that Ni incorporation can not only optimize the electronic structure to enhance the electrical conductivity and charge transfer, but also downshift the d-band center from the Fermi level to facilitate the desorption of oxygen intermediates, resulting in improved activity. As a result, the optimal NiCoO_x solid solution hybrids present excellent catalytic performances in the UOR as well as the electro-oxidation of organic molecules.