N, P doped carbon nanotubes confined WN-Ni Mott-Schottky heterogeneous electrocatalyst for water splitting and rechargeable zinc-air batteries

Rational design on highly active and durable noble metal free electrocatalyst is extraordinarily important for the industrializations of rechargeable zinc air batteries (ZABs) and water splitting. Herein, we report a novel tri-functional electrocatalyst, N,P co-doped carbon nanotubes confined WN-Ni Mott-Schottky heterostructured nanoparticles (WN-Ni@N,P-CNT) via one-pot pyrolysis. Attributed to the WN-Ni Mott-Schottky heterostructure, water dissociation and charge transfer at atomic level are accelerated; thereby, WN-Ni@N,P-CNT performs a Pt-like hydrogen evolution (HER) catalytic activity at high current density. Moreover, a superior oxygen evolution reaction (OER) activity is also achieved for WN-Ni@N,P-CNT demanding 268 mV overpotential to reach 10 mA cm−2, 52 mV lower than commercial IrO2; thus, merely 1.57 V is demanded to attain 10 mA cm−2 for overall water splitting in alkaline medium. Furthermore, half-wave potential for WN-Ni@N,P-CNT (0.84 V vs. RHE) is also similar to the benchmarked Pt/C. Owing to the superior ORR and OER activities, the power density of the assembled rechargeable ZAB outperforms Pt/C||IrO2 by a factor of 1.8 (126.2 mW cm−2 vs 71 mW cm−2). The exceptional battery performance is well-maintained after 330 h discharge-charge process due to the unique structure, in which Ni-WN hetero-nanoparticles are confined by N,P-CNT.