A co-axial structure composed of RuO2 on defective N-doped carbon nanotubes as a highly efficient electrocatalyst for overall water splitting

Abstract

The rational development of catalysts with high efficiency and stability for facilitating the hydrogen evolution reaction and the oxygen evolution reaction (HER/OER) is of immense importance in the process of overall water splitting (OWS). Herein, the synthesis of a co-axial structure composed of RuO₂ on defective N-doped carbon nanotubes (RuO₂-DNCTs) via a facile self-template strategy is reported. Due to their hollow co-axial interior structure which increases their catalytic activity and conductive capacity, RuO₂-DNCTs exhibit remarkable HER and OER performance. In particular, the mass activity of RuO₂-DNCTs for HER is 3.9 times superior to that of commercially available Pt/C. A bi-functional RuO₂-DNCT-based alkaline electrolyzer is developed for overall water splitting (OWS), exhibiting remarkable durability and a low cell potential of merely 1.48 V for achieving 10 mA cm². Density functional theory (DFT) suggested that the optimization of the adsorption energy for Ru sites during the OER process can be achieved by transferring electrons from defective nitrogen-doped carbon (DNC) to RuO₂, leading to a reduction in the reaction barrier and enhancement in reaction kinetics.