Increased crystallinity of RuSe₂/carbon nanotubes for enhanced electrochemical hydrogen generation performance

Ru-Based catalysts are significant in the green hydrogen generation via the electrochemical water-splitting reaction. Herein, it is found that the increased crystallinity of cubic RuSe₂ nanoparticles anchored over carbon nanotubes (RuSe₂/CNTs) could largely increase the hydrogen generation performance both in acidic and alkaline electrolytes. The freshly prepared RuSe₂/CNTs with low crystallinity had a very low catalytic performance for the HER, while the catalytic ability could be largely boosted by facile thermal annealing at 650 °C in an N₂ atmosphere, resulting from the increased crystallinity and electronic effect. The crystal structure enhancement of the RuSe₂ nanoparticles was well supported by the X-ray diffraction technique and the lattice fringes in the high-resolution transmission electron microscopy images. As a result, the catalyst exhibited largely improved catalytic performance compared to the freshly prepared RuSe₂/CNTs; specifically, the overpotentials of 48 and 64 mV were required to drive 10 mA cm^-2 in alkaline and acidic media when loaded on a glassy carbon electrode, much less than those of 109 and 120 mV for the freshly prepared RuSe₂/CNTs; the catalytic performance in the alkaline electrolyte was even close to that of the commercial Pt/C catalyst. Correspondingly, the improved catalytic stability, catalytic kinetics, charge transfer ability and catalytic efficiency of the active sites were also observed. The current work shows an effective approach and important understanding for catalytic performance enhancement via increased crystallinity by facile thermal annealing.