Flash synthesis of ultrafine and active NiRu alloy nanoparticles on N-rich carbon nanotubes via joule heating for efficient hydrogen and oxygen evolution reaction

The design and controlled synthesis of high-performance alloy nanoparticles as bifunctional electrocatalysts towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great industrial importance, but remains a great challenge. However, most of the prepared bimetallic alloys display unsatisfactory catalytic activity. Herein, NiRu alloy nanoparticles well-dispersed on N-rich carbon nanotubes (NiRu-CNTs) with a strong metal-support interaction (SMSI) are prepared through a flash Joule heating method in 0.5 s. Impressively, NiRu-CNTs exhibit remarkable HER activity under 1.0 M KOH solution with quite a small overpotential of 5.1 mV to reach the current density of 10 mA cm−2. In addition, superior HER stability up to 10 h with no noticeable current density degradation is realized. As expected, NiRu-CNTs exhibits excellent OER performance with a small overpotential of 270 mV at 10 mA cm−2, small Tafel slope of 54.1 mV dec−1, and long-term durability over 5000 CV cycles. When used in two-electrode electrolyzer for overall water splitting, NiRu-CNTs displays a low voltage of 1.85 V at 100 mA cm−2. This eco-friendly and cost-effective synthesis approach can be extended to the rational synthesis of various alloy catalysts with different metal species.