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• 2D interconnected NiTe/NF nanosheets was prepared by one-step hydrothermal method. • Annealing temperatures have an effect on crystal phase change and HER performance. • It leads to a positive shift of the d-band center on non-stoichiometric Ni 2.86 Te 2. • The Ni 2.86 Te 2 /NF exhibits superior HER performance compared to NiTe/NF. The non-stoichiometric Ni 2.86 Te 2 /NF was prepared by hydrothermal method combined with annealing process. Experimental and theoretical results demonstrate that the transition of crystal phase structure from NiTe to Ni 2.86 Te 2 leads to a strong electronic interaction between tellurium and nickel accompanying with the positive shift of the d-band center, resulting in improving the HER activity compared to the NiTe/NF. [Display omitted] It is of great significance to develop low cost, high-efficiency and environment-friendly electrocatalysts for hydrogen evolution reaction (HER) from water splitting. Herein, nickel telluride nanosheets grown on Ni Foam (NF) with three different crystal phases (NiTe, Ni 2.6 Te 2 and Ni 2.86 Te 2) are fabricated by one-step hydrothermal tellurization followed annealing process. The non-stoichiometric Ni 2.86 Te 2 /NF exhibits superior electrocatalytic HER performance compared to the NiTe/NF and Ni 2.6 Te 2 /NF, which is comparable to the state-of-the-art 20 wt% Pt/C catalyst at high current density. The Ni 2.86 Te 2 /NF only requires an overpotential of 348 mV to drive the current density of 200 mA cm−2 in a 1.0 M KOH electrolyte. Similarly, The Ni 2.86 Te 2 /NF delivered current densities of 200 mA cm−2 at the overpotential of 279 mV in 0.5 M H 2 SO 4. Such excellent performance could be ascribed to the fast electron transfer and positive shift of d d-band center from its rich defective effect of crystal phase transition, as well as to the exposure of active sites provided by the two-dimensional nanosheets with large specific surface area. This work provides valuable insights for the rational modulation of the crystal phase on the nickel telluride for catalyzing HER. [ABSTRACT FROM AUTHOR]

Designing highly active and durable catalysts is considered to be crucial for enhancing hydrogen evolution reaction (HER) from water electrolysis. Although some studies indicate that anatase TiO 2 is a promising candidate for electrolytic hydrogen evolution reaction, the influence of different crystalline phases of TiO 2 on the supported Ru catalysts for electrocatalytic HER performance is rarely systematically explored. Herein, a series of Ru/TiO 2 -X (X = R (Rutile), A (Anatase), and P25) catalysts were prepared to investigate the influence of the rutile and anatase phases of TiO 2 on the catalytic activity of Ru catalysts in HER. The findings demonstrate that the HER activity is much affected by the variation of the titania structure, when other factors are kept constant. The 15Ru/TiO 2 -R-H 2 has superior HER performance with a small overpotential of 63 mV to achieve a current density of 10 mA cm−2 in acidic electrolyte and 99 mV in alkaline electrolyte compared to 15Ru/TiO 2 -A-H 2 and 15Ru/TiO 2 -P25-H 2. This might be attributed to the faster electron transfer and lower Fermi level caused by the oxygen vacancy (V O) and strong metal-support interaction (SMSI), along with the exposure of active sites afforded by the highly dispersed ruthenium nanoparticles on the rutile TiO 2. Our results indicate that the presence of rutile TiO 2 support alone is adequate to maintain Ru in its most active form and make it a more performing catalyst, compared to anatase titania and P25. • Ru is supported on different crystalline phase of TiO 2 for electrocatalytic HER. • Partial Ru is incorporated the lattice of TiO 2 -R with SMSI effect. • Highly dispersed Ru and rich V O promote electrocatalytic HER. • Electron transfer from V O and Ti to surface Ru is conducive to optimizing HER. [ABSTRACT FROM AUTHOR]