Colloidal Synthesis of Mo–Ni Alloy Nanoparticles as Bifunctional Electrocatalysts for Efficient Overall Water Splitting

Abstract The practical use of overall water electrolysis is largely hindered by the need for precious noble metal‐based catalysts. Here, the colloidal synthesis of earth‐abundant electrocatalysts of Mo–Ni nanoparticles for efficient water splitting by thermal decomposition of Ni(acac) 2 and Mo(CO) 6 in the presence of 1‐octadecene and oleylamine at 320 °C is reported. It is shown that the optimized catalysts (Mo 0.6 Ni 0.4 ) only require low overpotentials of 0.065 V for the hydrogen evolution reaction (HER) and of 290 mV for the oxygen evolution reaction (OER) to deliver a current density of 10 mA cm −2 in KOH (1.0 m ). The as‐prepared Mo–Ni alloy nanoparticles also show extraordinary durability for both the HER and OER. A low potential of ≈1.62 V is required to yield a current density of 10 mA cm −2 when utilizing the alloy nanoparticles as bifunctional catalysts in a two‐electrode electrolyzer system. The ease of preparing either rigid or flexible high‐performance electrodes by making use of the alloy nanoparticle electrocatalysts without the need for binder further suggests the attractive application of colloidally stable nanoparticles in the field of electrochemical water splitting.