Morphology and composition regulation of Prussian blue analogues to boost electrocatalytic oxygen evolution reaction

Prussian blue analogues (PBAs) have well-dispersed active sites and porous nanostructure. Reasonable design and construction of the nanostructure of PBAs is a promising option to obtain cost-effective electrocatalysts for high-efficiency oxygen evolution reaction (OER). Nevertheless, current structural engineering is costly and complex due to the inevitable involvement of additional etching agents or procedures. In this paper, a simple temperature-control strategy without additional etchant, is presented for the preparation of hollow CoFe-PBA precursors with porous nanobox structure, and then the hollow CoFe-PBA@NiFeRu-LDH nanoboxes (named as CoFe-PBA@NiFeRu-LDH NBs) heterogeneous catalyst is obtained. The preferable composition and structure provide more accessible active sites and better electronic structure for OER. As a result, the optimized CoFe-PBA@NiFeRu-LDH NBs demonstrates an impressive ability to accelerate OER in alkaline electrolyte with a minimal overpotential (219 mV at 10 mA cm^-2) and excellent stability. More importantly, by combining CoFe-PBA@NiFeRu-LDH NBs with Pt/C for overall water electrolysis, an ultra-low voltage (1.52 V at 10 mA cm^-2) is required. This study offers a facile and effective idea for chemical and morphological control in the manufacture of efficient electrocatalysts.