Laser-reduced graphene oxide for metal-free electrocatalysis

This study presents a comparative analysis of short and ultrashort-pulsed laser-induced reduction of graphene oxide (GO) films, placing emphasis on the critical influence of laser pulse duration on the reduction process and material properties. Through systematic experiments, using femtosecond (170 fs), picosecond (150 ps) and nanosecond (1 ns) infrared laser pulses on GO films of 100 and 200 nm thickness, we demonstrate that pulse duration plays a significant role in the GO reduction process and the resulting electrical conductivity of laser-reduced graphene oxide (LrGO). Optimal laser parameters, including pulse duration and energy, are identified for achieving a highly conductive LrGO surface, with the best performing films reaching sheet resistance values below 140 Ω sq −1 . The interplay between pulse duration, GO film thickness and reduction efficiency has been investigated and discussed. Notably, the best reduced LrGO layer exhibits superior performance as a metal-free electrocatalyst for hydrogen production. In electrochemical tests for hydrogen evolution reaction, LrGO produced under optimal reduction conditions, specifically under femtosecond irradiation, shows significantly enhanced catalytic activity, achieving a current density of 381 μA cm −2 , attributed to its high conductivity and the beneficial defect structures introduced during laser reduction. Our results establish that all three factors, including the reduction level, film thickness, and laser pulse duration, synergistically determine the catalytic activity of LrGO. By tuning such parameters, we achieve substantial enhancements in hydrogen generation performance, indicating the strong potential of laser-engineered GO films for efficient hydrogen production.