Ultrafast microwave construction of stabilized RuCo alloys for overall water splitting

Abstract

Ruthenium-based catalysts are considered efficient and cost-effective potential alkaline electrolysis water catalysts that exhibit both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities. Therefore, it is crucial to develop straightforward and low-energy synthesis methods for ruthenium-based alloy catalysts. In this study, we present a microwave synthesis approach for rapidly fabricating RuCo alloy supported on copper foam. Microwave heating, with its unique heating method, enables the efficient and rapid synthesis of alloy particles in a very short period of time. The synthesized RuCo/Cu2O/CF demonstrates excellent bifunctional HER and OER activities in alkaline media. Compared to commercial precious metal catalysts, RuCo/Cu2O/CF exhibits lower overpotentials and improved electrocatalytic kinetics, with an overpotential of 43 mV (10 mA cm−2) for HER and a Tafel slope of 37.6 mV dec−1, and an overpotential of 253 mV (10 mA cm−2) for OER, also with a Tafel slope of 189.1 mV dec−1. Moreover, the synthesized RuCo/Cu2O/CF shows remarkable stability. Theoretical calculations indicate that after alloying with Ru, both the water dissociation energy barrier and hydrogen adsorption energy on the Co surface are optimized. In a symmetric dual-electrode system, the RuCo/Cu2O/CF electrolyzer requires only 1.56 V to achieve a current density of 10 mA cm−2, outperforming commercial precious metal catalysts while exhibiting excellent long-term stability. These findings reveal a simple, low-energy preparation method for alloy catalysts, providing new insights into the development of water-splitting catalysts.