Selenium-transition metal supported on a mixture of reduced graphene oxide and silica template for water splitting

Exploration of economical, highly efficient, and environment friendly non-noble-metal-based electrocatalysts is necessary for hydrogen and oxygen evolution reactions (HER and OER) but challenging for cost-effective water splitting. Herein, metal selenium nanoparticles (M = Ni, Co & Fe) are anchored on the surface of reduced graphene oxide and a silica template (rGO-ST) through a simple one-pot solvothermal method. The resulting electrocatalyst composite can enhance mass/charge transfer and promote interaction between water molecules and electrocatalyst reactive sites. NiSe₂/rGO-ST shows a remarkable overpotential (52.5 mV) at 10 mA cm^-2 for the HER compared to the benchmark Pt/C E-TEK (29 mV), while the overpotential values of CoSeO₃/rGO-ST and FeSe₂/rGO-ST are 246 and 347 mV, respectively. The FeSe₂/rGO-ST/NF shows a low overpotential (297 mV) at 50 mA cm^-2 for the OER compared to RuO₂/NF (325 mV), while the overpotentials of CoSeO₃-rGO-ST/NF and NiSe₂-rGO-ST/NF are 400 and 475 mV, respectively. Furthermore, all catalysts indicate negligible deterioration, indicating better stability during the process of HER and OER after a stability test of 60 h. The water splitting system composed of NiSe₂-rGO-ST/NF||FeSe₂-rGO-ST/NF electrodes requires only ∼1.75 V at 10 mA cm^-2. Its performance is nearly close to that of a noble metal-based Pt/C/NF||RuO₂/NF water splitting system.