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[Display omitted] • The ultrathin RhIr NSs/NF was prepared by a simple and mild one-pot aqueous strategy at room temperature. • The unique sheet-like architectures provided large ECSA and exposed high-density active sites. • The self-supported RhIr NSs/NF had excellent HER activity and stability for the HER over a wide pH range. The development of low-cost and high-efficiency electrocatalysts is very important for electrocatalytic hydrogen evolution reaction (HER) in water splitting system. Herein, ultrathin rhodium-iridium nanosheets were facilely in-situ grown on nickel foam (RhIr NSs/NF) by a one-pot aqueous strategy at room temperature. The sheet-like structures with the film thickness of 78 nm were identified by scanning electron microscopy and transmission electron microscopy. The catalyst showed greatly high HER features in both 1.0 M KOH and 0.5 M H 2 SO 4 with the overpotentials of 15 and 14 mV to achieve 10 mA cm−2, respectively, surpassing most Pt-free catalysts. Also, the RhIr NSs/NF exhibited amazing catalytic stability during the long-term operation. This study offers a facile and rational pathway for design and synthesis of advanced HER electrocatalysts for energy conversion devices. [ABSTRACT FROM AUTHOR]

• The P-Co 2 MnO 4 /NF was synthesized by hydrothermal treatment, oxidation and P-doping. • The unique straw-like nanoneedle arrays provided large ECSA and rich active sites. • P-doping had the greatly improved HER activities. • The P-Co 2 MnO 4 /NF exhibited excellent HER activities in wide pH range of electrolytes. Developing high-performance and cut-price non-noble-metal electrocatalysts for hydrogen evolution reaction (HER) is desirable yet challenging. Herein, straw-like phosphorus-doped Co 2 MnO 4 nanoneedle arrays supported on nickel foam (P-Co 2 MnO 4 /NF) were prepared by successive hydrothermal treatment, oxidation and P doping for high-efficiency HER. Benefiting from the unique needle-like arrays and compositions advantages, P-Co 2 MnO 4 /NF exhibited excellent HER activities with the overpotentials of 33, 43 and 102 mV to afford a current density of 10 mA cm−2 in alkaline, acidic and neutral media, respectively, coupled with the long-term electrochemical stability. This work affords an effective avenue for preparation of cost-effectiveness, high-efficiency and wide-pH HER catalysts for electrochemical energy technologies. [ABSTRACT FROM AUTHOR]