Rational design of Ru aerogel and RuCo aerogels with abundant oxygen vacancies for hydrogen evolution reaction, oxygen evolution reaction, and overall water splitting

Developing efficient, robust, and cost-effective catalysts to boost the electrocatalytic properties of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for overall water splitting is fundamentally important yet very challenging. Herein, we report a facile method to prepare Ru-based aerogels for HER, OER, and water electrolysis. Specifically, Ru aerogel exhibits comparable HER performance with Pt/C, evidenced by a close overpotential at 10 mA cm−2, a smaller Tafel slope, and an outperformed long-term stability. Among a series of RuCo aerogels, the Ru0.7Co0.3 aerogel has the best OER performance superior to the RuO2 benchmark catalyst, with a very small overpotential of 272 mV at 10 mA cm−2, a low Tafel slope value of 41.6 mV dec−1, and the improved long-term durability. The excellent OER performance of the Ru0.7Co0.3 aerogel is mainly attributed to the RuCo synergistic catalytic effect, the abundant oxygen vacancies, and the structural merits of the sample. Notably, in the practical overall water splitting test, the combined Ru and Ru0.7Co0.3 aerogel catalyst outperforms the Pt/C + RuO2 couple. This study can shed light on preparation of metal aerogel-based bifunctional electrocatalyst for overall water splitting and beyond.