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Ti 2 Cu, TiCu and TiCu 4 were synthesized and their electrocatalytic activities for hydrogen evolution reaction (HER) were investigated. The hydrogen overpotential observed at 10 mA/ cm2 (η 10) followed the order Ti 2 Cu (η 10 = −215 mV) > TiCu (η 10 = −182 mV) > TiCu 4 (η 10 = −170 mV). The hydrogen adsorption energy (∆G Had) on Cu site of TiCu 4 is exergonic and close to optimal position (i.e. ∆G Had = 0). A synergistic effect was proposed to account for the excellent HER performance of these Ti Cu binary intermetallics compounds that could replace PGM and achieve Midas touch in the future. [Display omitted] • High purity of Ti 2 Cu, TiCu and TiCu 4 were synthesized by using rapid arc-melting technique. • Hydrogen evolution reaction (HER) study on Ti 2 Cu, TiCu and TiCu 4 in alkaline media. • HER activity of Ti 2 Cu, TiCu and TiCu 4 were explored by using density functional theory. • Synergistic effect for these Ti Cu binary intermetallics toward HER activity was discussed. [ABSTRACT FROM AUTHOR]

• Metallic Ni 3 Mo 3 N porous microrods showed a low overpotential of 44.6 mV to attain a current density of 10 mA cm−2 and superstability at a large current density of 1100 mA cm−2 for 50 h. • Density functional theory (DFT) calculations clarified that the Ni 3 Mo 3 N electrocatalyst possesses various HER catalytic active sites with suitable ΔG H* values (more than ten sites) due to the metallic semiconductor structure with special electronic structure. • The constructed NC/Ni 3 Mo 3 N/NF||NiMoO 4 ·xH 2 O/NF only needed a voltage of 1.58 V to attain a current density of 50 mA cm−2, which was better than that of 20 wt% Pt/C||RuO 2 (1.71 V), and has high potential for large-scale industrial applications. The low onset potential and large current density of electrocatalysts has always been important target for hydrogen evolution reaction (HER). In especial, the large current density (larger than 1000 mA cm−2) is an important criterion for the evaluation of electrocatalysts for industrial application. Usually, the number of catalytic sites in electrocatalyst limits the current density for HER. To overcome these problems, bimetallic nitride is controllably synthesized, and the corresponding catalytic sites are regulated by a bimetallic effect. Herein, an inexpensive electrocatalyst consisting of N-doped carbon-coated porous Ni 3 Mo 3 N microrods (NC/Ni 3 Mo 3 N/NF) is cultured on nickel foam using a hydrothermal reaction and subsequent nitriding process. The designed electrocatalyst consisting of porous NC/Ni 3 Mo 3 N microrods displays efficient catalytic activity for hydrogen evolution reaction (HER), with a small overpotential of 136 mV to achieve a cathodic current density of 100 mA cm−2. Density functional theory (DFT) calculations clarified that the Ni 3 Mo 3 N electrocatalyst possesses various HER catalytic active sites with suitable ΔG H* values (more than ten sites) due to the metallic semiconductor structure with special electronic structure. It is important that NC/Ni 3 Mo 3 N/NF possess perfect superstability for HER, with a large current density of 1100 mA cm−2 for 50 h. Lastly, NC/Ni 3 Mo 3 N/NF and NiMoO 4 ·xH 2 O/NF are hired as the cathode and anode, respectively, to assemble the two-electrode electrolytic cell, thereby achieving excellent overall water splitting performance with a voltage of 1.58 V at 50 mA cm−2 in 1 M KOH aqueous solution. [ABSTRACT FROM AUTHOR]