Ru-RuO2/CNT hybrids as high-activity pH-universal electrocatalysts for water splitting within 0.73 V in an asymmetric-electrolyte electrolyzer.

Exploring high-activity electrocatalysts for water electrolysis is a pivotal field of hot research as hydrogen is a very promising renewable energy source and bountiful in supply. Understanding the structure–composition–property relationships is the key for engineering improved electrocatalysts. We herein report a rational design on Ru-RuO 2 hybrid nanoparticles decorating carbon nanotubes composites electrocatalysts (Ru-RuO 2 /CNT), which shows impressively high activity toward hydrogen/oxygen evolution reaction (HER/OER) in all pH aqueous electrolytes. The Ru-RuO 2 /CNT, as an OER catalyst, requires ultralow overpotentials of 0.18 V, 0.27 V and 0.21 V to drive the current density of 10 mA cm⁻² in acidic, neutral and alkaline media, respectively. Meanwhile, the catalyst also exhibits superior HER activity with the current density of 10 mA cm⁻² at −0.063 V, −0.048 V and −0.012 V in acidic, neutral and alkaline media, respectively. Systematic characterizations and comprehensive electrochemical studies coupling with theoretical calculations verify that Ru favorably works with RuO 2 and CNT to synergistically contribute such highly desirable electrocatalytic activity. The bifunctional catalytic properties, in conjunction with its pH-universal compatibility, inspire us to an asymmetric-electrolyte electrolyzer was set up, which can harvest the electrochemical neutralization energy with implementing electrolysis H 2 generation with a current density of 10 mA cm⁻² at an applied voltage of 0.73 V. The as-developed asymmetric-electrolyte electrolyzer, by coupling high-activity but not too expensive electrocatalysts with optimizing the catalytic efficiency in their favorable electrolyte, potentially provides an environmental-friend and energy-saving avenue for the future electrolysis H 2 generation. Image 1 • Bifunctional electrocatalysts for All-pH-electrolyte HER and OER. • High catalytic activity, good durability, and low cost. • Electrochemical neutralization energy was harvested for assisting electrolysis H 2 generation. • Water electrolysis in an asymmetric-electrolyte electrolyzer was implemented within 0.73 V. [ABSTRACT FROM AUTHOR]