Carbon quantum dots/cobalt chalcogenide porous nanofibers for highly efficient electrocatalytic hydrogen evolution

Abstract

Hydrogen is increasingly needed as a clean energy source with high energy density. Hydrogen evolution reaction (HER) via electrocatalysis is a viable way to produce clean hydrogen. The key to achieving active HER is to select highly-active electrocatalysts. Although Pt-based noble metal catalysts have excellent performance, they are expensive and earth-abundant. Compared to noble metals, cobalt chalcogenide has been used for efficient HER. Here, we first demonstrated a porous material based on C-dots/cobalt chalcogenide nanofibers as an effective electrocatalyst for HER. Co3O4/10 wt% C-dots nanofibers-based electrode reached an overpotential of 383 mV at the current density of 10 mA·cm−2 with Tafel slope of 93.4 mV·dec−1 in 1 M KOH, which is much better than bare Co3O4 (758 mV at 10 mA·cm−2, Tafel slope is 111.3 mV·dec−1). In addition to the excellent HER performance, the Co3O4/C-dots nanofibers performed very well in terms of stability after a 10-hour operation, and the overpotential was even reduced by 6.7%. With the further sulphuration, the Co3S4/C-dots nanofibers exhibited an overpotential of 280.2 mV at the current density of 10 mA·cm−2. This work indicates that the C-dots can be used as an efficient additive for cobalt chalcogenide based electrocatalysts.