Promoting Electrocatalytic Oxygen Evolution over Transition-Metal Phosphide-Based Nanocomposites via Architectural and Electronic Engineering.

Exploring noble-metal-free advanced electrocatalysts for oxygen evolution reaction (OER) is of great significance for development of sustainable energy systems. Rationally engineering chemical composition, electronic structure, and micro/nanoarchitecture of these catalysts represent a promising way to achieve their desired performance. Herein, we propose a general synthetic approach to prepare a series of porous nanosheets of bi- and tritransition-metal phosphides with homogeneous compositions supported by reduced graphene oxide (the resultant samples are termed as rGO/MaMb-P for simplicity, including rGO/CoFe-P, rGO/NiFe-P, rGO/CoNi-P, and rGO/CoNiFe-P). The resultant sheet-on-sheet hierarchical nanocomposites exhibit outstanding OER performance with low overpotentials, small Tafel slopes, and long durability in alkaline electrolyte, which compete favorably with the state-of-the-art OER catalysts reported to date. The remarkable electrocatalytic performances originate from their hierarchical structures and tailorable compositions with optimized electronic structure modulation and synergistically electroactive sites, together with large active surface area and smooth mass/charge transports. This synthetic route could serve as a facile and controllable process to simultaneously realize the architectural manipulation, compositional regulation, and electronic modulation for low-cost OER electrocatalysts based on earth-abundant metal elements in practical water electrolysis and other energy applications.