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In this work, we report a facile method to prepare P, N co‐doped porous carbon (PNPC) by the carbonization of covalent organic polymer (COP) used as efficient metal‐free electrocatalyst for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Overpotential is only 150 mV for the PNPC electrocatalyst to reach 10 mA cm−2 in the acidic medium due to the heteroatom dopants in the carbon matrix; meanwhile, stable HER activity is recorded during 5000 potential cycles. Additionally, overpotential is 343 mV for PNPC electrocatalyst to drive OER catalysis with 10 mA cm−2, which is comparable to the benchmarked IrO2 (320 mV). Similarly, PNPC electrocatalyst can achieve a Pt‐like ORR catalytic activity. The power density of the assembled rechargeable zinc‐air battery (ZAB) is 1.8 times higher than that of the commercial system (Pt/C−IrO2) and charge‐discharge voltage gap is well maintained during 20 h test, implying the high stability of the formed PNPC electrocatalyst. [ABSTRACT FROM AUTHOR]

Highly active and stable electrocatalysts at low cost for hydrogen evolution reaction are essential for large scale hydrogen production. The Ni 3 P-Ni heterostructure confined in 3D networks of carbon nanotube (CNT) has been successfully prepared as the hydrogen evolution reaction (HER) electrode. The morphology and phase composition of Ni 3 P-Ni heterostructure are tunable by varying the acid pickling time. The Ni 3 P-Ni/CNT composite electrode with optimized Ni:Ni 3 P ratio of 22.29 wt% demonstrate high catalytic activity and excellent stability for HER. It demonstrates a comparable HER activity to the standard Pt electrode in alkaline solution, i.e., overpotentials of 116 vs 67 mV at 10 mA·cm−2 and Tafel slops of 59 vs 37 mV·dec−1. No degradation is observed after 1000 cyclic voltammetry (CV) cycles or 50 h operation under constant 0.3 V overpotential. • Pickling affects the morphology of heterogeneous structure and the content of Ni. • The Ni 3 P-Ni heterostructure was anchored to the carbon nanotube network by ball milling. • The electrode was prepared by mixing with PTFE and pressing. • The results show that Ni 3 P-Ni/CNT electrode has the best hydrogen evolution activity when the Ni/Ni 3 P ratio is 22.29 %. [ABSTRACT FROM AUTHOR]