Interfacial engineering and hydrophilic/aerophobic tuning of Sn4P3/Co2P heterojunction nanoarrays for high-efficiency fully reversible water electrolysis

The simultaneous integration of electronic regulation and architectural engineering in one electrocatalyst represents a powerful leverage to concurrently boost the electrocatalytic performance towards overall water splitting. We herein rationally fabricate Sn 4 P 3 /Co 2 P “stalk”-“cap”-typed nanoarrays (Sn 4 P 3 /Co 2 P SCNAs) with abundant heterointerfaces and elaborately implanted “caps”. The nanoarrayed structure can substantially enlarge the exposure of active sites and promote the mass/electron transport, thus accelerating the reaction kinetics. Moreover, the purposely grafted “caps” are beneficial to increase the hydrophilicity/aerophobicity, which facilitate the water affinity and release of generated gas bubbles. Accordingly, the obtained Sn 4 P 3 /Co 2 P SCNAs deliver exceptional electrocatalytic performances towards the HER and OER, as reflected by the overpotentials of 45.4 and 280.4 mV at 10 mA cm −2 , respectively. More impressively, the two-electrode electrolyzer assembled by freestanding Sn 4 P 3 /Co 2 P SCNAs requires a cell voltage of 1.56 V at 10 mA cm −2 and exhibits superior stability and full reversibility, holding great potential in practical water electrolysis. • Heterostructured Sn 4 P 3 /Co 2 P SCNAs (“stalk”-“cap”-typed nanoarrays) are fabricated. • Sn 4 P 3 /Co 2 P SCNAs possess regulated electronic structure and increased active sites. • The hydrophilicity/aerophobicity of Sn 4 P 3 /Co 2 P SCNAs benefit gas-releasing reactions. • Sn 4 P 3 /Co 2 P SCNAs exhibit robust electrocatalytic performance and full reversibility.