Designing of CoP4/FeP4 with hollow nanocages as bifunctional catalysts for overall water splitting

Efficient and stable electrocatalysts are essential for water splitting. Feasible structural design can facilitate electron transport and increase specific surface area. Herein, the porous CoP₄/FeP₄ hollow cubes are synthesized by two steps: synthesizing the Co–Fe prussian blue analogues via co-precipitation and phosphating it by calcination. The construction of heterojunction in CoP₄/FeP₄ not only accelerates electronic transmission but also provides active sites, which acts synergistically on the oxygen and hydrogen evolution reactions. Therefore, the CoP₄/FeP₄ hollow cubes with the exist of mesoporous exhibit the promising performance for water splitting. The enhanced performance that basically originates from bimetallic synergy and unique morphological structure is acquired with a low overpotential of 270 mV at 10 mA cm^?2 and the Tafel slope of 42.4 mV dec^?1 towards the oxygen evolution reaction (OER). Electrolyzer with two-electrode system assemble by utilizing the CoP₄/FeP₄ hybrid as anode and cathode exhibits a cell voltage of 1.74 V to achieve 10 mA cm^?2 for overall water splitting. This study that provides a simple strategy to design and construct the heterogeneous interface may promote the development of non-noble metal for HER and OER.