Ultra-small-sized multi-element metal oxide nanofibers: an efficient electrocatalyst for hydrogen evolution.

Compared to noble metals, transition metal oxides (TMOs) have positive development prospects in the field of electrocatalysis, and the synergy between the elements in multi-element TMO-based materials can improve their catalytic activity. However, it is still a challenge to synthesize multi-component TMO-based catalysts and deeply understand the effects of components on the catalytic performance of the catalysts. Here, we demonstrate multi-element ultra-small-sized nanofibers for efficient hydrogen production. The ternary NiFeCoO nanofiber-based electrode reached an overpotential of 82 mV at the current density of 10 mA cm -2 with a Tafel slope of 56 mV dec -1 in 1 M KOH, which are close to those of Pt plate (66 mV at 10 mA cm -2 ; the Tafel slope is 32 mV dec -1 ). In addition, the current density maintained 97% of its initial value after 10 h operation. We used the ternary NiFeCoO nanofiber-based electrode as an efficient counter electrode in photoelectrochemical hydrogen production to demonstrate the versatility of these nanofibers.