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Molybdenum disulfide has attracted significant research attention as a nanocatalyst for hydrogen evolution reaction. In this study, the effects of nanoribbons on the catalytic performance of molybdenum disulfide in the hydrogen evolution reaction are evaluated via the density functional theory. Co is considered to be an effective promoter of Mo-based catalysts. Thus, the promotion of the Mo-edge was studied here in a number of Co-substituted surface models. The results show that the electronic structure of the molybdenum disulfide nanoribbons changed after doping with Co atoms; this change significantly reduced the Gibbs free energy of the hydrogen evolution reaction and improved the reaction activity. In addition, the effects of stress regulation on the catalyst were analyzed. Tensile and compressive stresses were applied to the catalyst in the x direction. The results indicate that the distance between atoms changed owing to the effects of stress, and changes were also observed in the electronic properties. The insights obtained from this study will be helpful to further improve the activity of catalysts. [ABSTRACT FROM AUTHOR]

With practical electrocatalytic hydrogen production frequently involving the splitting of water in various pH media, there is an urgent need but still a technical challenge to develop low-cost, highly active, and stable electrocatalysts for pH-universal hydrogen evolution reaction (HER). We report herein the adoption of a hydrothermal reaction combined with a post gas-phase doping strategy to fabricate P-doped NiCo2Se4 hollow nanoneedle arrays on carbon fiber paper (i.e., P−NiCo2Se4/CFP). Notably, the optimal arrays (P8.71−NiCo2Se4/CFP) can afford an outstanding pH-universal HER performance, with an overpotential as low as 33, 57, and 69 mV at 10 mA·cm−2 and corresponding Tafel slopes down to 52, 61, and 72 mV·dec−1 in acidic, alkaline, and neutral media, respectively, outperforming most state-of-the-art nonprecious catalysts and even the commercial Pt/C catalyst in both neutral and alkaline media at large current densities. Impressively, P8.71−NiCo2Se4/CFP also displays good durability toward long-time stability testing in harsh acidic and alkaline electrolytes. Experimental and theoretical studies further reveal that the doping of P atoms into NiCo2Se4 can simultaneously optimize its H* adsorption/desorption energy, water adsorption energy, and water dissociation energy by adjusting the local electronic states of various active sites, thus accelerating the rate-determining step of HER in different pH media to endow P−NiCo2Se4 with an outstanding pH-universal HER performance. This work provides atomic-level insights into the roles of active sites in various electrolysis environments, thereby shedding new light on the rational design of highly efficient pH-universal nonprecious catalysts for HER and beyond. [ABSTRACT FROM AUTHOR]

As compared to solar-blind ultraviolet (UV) photodetectors (PDs), far-UVC PDs not only show some irreplaceable advantages but also are more challenging to be developed. To solve this challenge, we report herein a soft template-assisted solvothermal route to synthesize ultrathin γ-Ga 2 O 3 quantum wires (UQWs) with diameters down to 1-2 nm. These UQWs all exhibit a cluster-like absorption feature with a strong peak located between 190 and 230 nm and an edge below 250 nm, allowing highly selective absorption to far-UVC light. Notably, their normalized absorption coefficients were experimentally and theoretically confirmed to increase obviously with decreasing their diameters. Self-powered photoelectrochemical-type PDs based on Ga 2 O 3 QWs of 1.7 nm diameter were therefore fabricated, exhibiting an excellent far-UVC detection performance with an unprecedented ultrahigh spectral selectivity ( R 210 nm / R 250 nm = 452). As a proof of concept, this paper offers a new idea for developing ultrawide bandgap semiconductor materials and devices by leveraging a strong quantum confinement effect.