RuO 2 nanoparticles anchored on g-C 3 N 4 as an efficient bifunctional electrocatalyst for water splitting in acidic media.

The electrolysis of water, particularly proton exchange membrane (PEM) water electrolysis, holds great promise for hydrogen production in industry. However, the catalyst used in this process is prone to dissolution in acidic environments, making it imperative to develop cost-effective, highly efficient, and acid-stable electrocatalytic materials to overcome this challenge and enable large-scale application of PEM water electrolysis technology. Herein, we prepared ruthenium oxide (RuO 2 )/graphitic carbon nitride (g-C 3 N 4 ) composites (RuO 2 /C 3 N 4 ) via a combination of sol-gel and annealing methods. The g-C 3 N 4 provides a large surface area, while RuO 2 is uniformly deposited on the g-C 3 N 4 surface. The interaction between g-C 3 N 4 and RuO 2 stabilizes the RuO 2 nanoparticles and enhances long-term water oxidation stability. This unique structure and the combined advantages of RuO 2 and g-C 3 N 4 yield exceptional electrocatalytic activity toward both the oxygen evolution reaction (OER, 240 mV@10 mA cm -2 ) and the hydrogen evolution reaction (HER, 109 mV@10 mA cm -2 ), with excellent durability (over 28 h), and a cell voltage of 1.607 V at 10 mA cm -2 when used in an RuO 2 /C 3 N 4 ||RuO 2 /C 3 N 4 electrolyzer. This study highlights the efficacy of the g-C 3 N 4 support method in designing highly stable Ru-based OER electrocatalysts for efficient acidic water splitting.