Polyaniline-coated Ru/Ni(OH)2 nanosheets for hydrogen evolution reaction over a wide pH range

How to improve the performance of ruthenium (Ru)–based catalysts for hydrogen evolution reaction (HER) to replace Pt is an interesting topic. Here, we in situ synthesize a polyaniline (PANI)-coated ultralow Ru-doped Ni(OH)2 nanosheet ([email protected]) in a 3D integral electrode via a facile dissolution–precipitation strategy and electrodeposition. Results indicate that [email protected] has a small overpotential of 21.9 mV at a current density of 10 mA cm−2 and a low Tafel slope of 38.54 mV dec−1 in alkaline condition, which is comparable with that of 20% Pt/C. The outstanding performance is attributed to the synergistic effects of the Ru-doped 2D Ni(OH)2 structure, active metallic Ru cluster, PANI coating and 3D integrated Ni electrode. Owing to PANI coating, [email protected] shows excellent durability with the increase of 36.8% current density retention (from 52.2% for RuNi-NSs increasing to 89% for [email protected]) compared to the RuNi-NSs sample without PANI coating in strong acidic medium, because the PANI coating could keep H+ from cracking the catalyst structure and therefore enhance the stability. In short, this work indicates that [email protected]ANI composite is an excellent wide pH range HER catalyst.