Regulating the H adsorption on supported RuO2 toward efficient Hydrogen evolution catalysis

The development of bifunctional Ru-based electrocatalysts with high efficiency for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic electrolytes is highly desirable. However, most Ru-based catalysts display inadequate HER activity and unsatisfactory OER stability. Herein, we present a facile synthesis of a heterojunction catalyst by confining RuO 2 nanoclusters on Fe 3 O 4 nano-capsules substrates (named RuO 2 @Fe 3 O 4 ). The RuO 2 @Fe 3 O 4 , with its unique morphology facilitating efficient site accessibility and rapid mass transfer, exhibits excellent HER activity with a low overpotential of 79.5   mV and a large exchange current density of 1.12   mA   cm -2 . Remarkably, RuO 2 @Fe 3 O 4 demonstrates exceptional durability, maintaining 100   h at 100   mA   cm -2 with only 5.9% activity decay. Additionally, the RuO 2 @Fe 3 O 4 catalyst displays prominent oxygen OER activity and stability. Density functional theory (DFT) calculations confirm that electron transfer from Fe to Ru optimizes the hydrogen adsorption energy of the Ru site, making it the main active site. This work provides a viable route for developing bifunctional Ru-based catalysts.