A facile preparation strategy for lignin-based carbon encapsulate cobalt/cobalt phosphides heterojunctions for boosting acidic hydrogen evolution reaction

The coupling of cobalt and cobalt phosphides has been demonstrated to be an efficient strategy to enhance the catalytic activity for hydrogen evolution reaction (HER). Herein, the lignin-based carbon encapsulated cobalt/cobalt phosphides heterojunctions (Co/Co2P@LGC) was synthesized successfully on the lignin-based carbon by carbothermal reduction integrated with post-phosphidation. The strong coupling interaction in the heterostructure promoted the establishment of a distinct synergy effect between Co and P atoms, resulting in the redistribution of electronic structure. The outstanding porous sheet structure of lignin-derived carbon facilitated the exposure of more accessible active sites and self-dopants were conducive to the formation of more carbon defects. As expected, the best catalysts, Co/Co2P@LGC-450 exhibited excellent HER performance in 0.5 M H2SO4, which afford a current density of 10 mA/cm2 with only 150 mV and a Tafel slope of 86 mV dec−1, as well as a robust stability for 120 h at 10 mA cm−2. This research not only presented a facile method for heterostructure electrocatalysts preparation, but also offered crucial insights into the lignin valorisation.