Graphene Decorated with Uniform Ultrathin (CoP)_x -(FeP)_1-x Nanorods: A Robust Non-Noble-Metal Catalyst for Hydrogen Evolution

Developing high-performance but low-cost hydrogen evolution reaction (HER) electrocatalysts with superior activity and stability for future sustainable energy conversion technologies is highly desired. Tuning of microstructure, configuration, and chemical composition are paramount to developing effective non-noble electrocatalysts for HER. Herein, a universal "nanocasting" method is reported to construct graphene decorated with uniform ternary (CoP)_x -(FeP)_1-x (0 ≤ x ≤ 1) nanorods hybrids with different chemical compositions [(CoP)_x -(FeP)_1-x -NRs/G] as a highly active and durable nonprecious-metal electrocatalyst for the HER. The optimized (CoP)_0.54 -(FeP)_0.46 -NRs/G electrocatalyst exhibits overpotentials of as low as 57 and 97 mV at 10 mA cm^-2 , Tafel slopes of 52 and 62 mV dec^-1 , exchange current densities of 0.489 and 0.454 mA cm^-2 , and Faradaic efficiency of nearly 100% in acidic and alkaline media, respectively. More importantly, this electrocatalyst also exhibits high tolerance and durability in a wide pH range and keeps catalytic activity for at least 3000 cycles and 24 h of sustained hydrogen production. The excellent catalytic performance of the (CoP)_x -(FeP)_1-x -NRs/G electrocatalyst may be ascribed to its unique mesoporous structure and strong synergistic effect between CoP and FeP. Thus, the work provides a feasible way to fabricate cheap and highly efficient electrocatalyst as alternatives for Pt-based electrocatalysts for HER in electrochemical water splitting.