Controllable atomic engineering of N into 1T′-phase ReS2 regulates the electronic structure and leads to enhanced alkaline hydrogen evolution.

MoS2/Co9S8 heterostructures were in situ grown on three-dimensional carbon network substrates with interconnected hierarchical pores, exhibit excellent alkaline HER activity.

Nanotransition-metal based carbide (TMC) electrocatalysts owing to the desirable metallic properties and platinum-like d-band electronic configuration have arisen as potential hydrogen evolution reaction (HER) electrocatalysts recently. Nevertheless, the correlation between cation incorporation and the intrinsic catalytic performance of bimetallic TMC-based electrocatalysts is still ambiguous. In addition, low-cost and simple preparation methods need to be further developed. Herein, a template-assisted method was developed to synthesize nanoscale metallic cobalt-doped β-Mo2C nanoparticles (Co-MC NPs), which were embedded in a two-dimensional graphite carbon nanosheet (2DGC) current collector. The obtained catalytic material has a rich pore structure and excellent electron transport properties due to the ingenious preparation method. Furthermore, it was revealed with electrochemical characterization and density functional theory (DFT) simulation that Co atom substitution could effectively weaken the strength of proton adsorption at the coordination of Mo and C atoms and synchronously facilitate the H2 desorption from the active sites of Co-MC/2DGC nanostructures. Therefore Co-MC/2DGC nanoparticles display a superior HER catalytic performance; that is, an overpotential of 103 mV is required to reach a current density of 10 mA cm–2 with a Tafel slope of 76.9 mV dec–1 along with an outstanding stability in alkaline.

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As a result, it is critical to design a lowcost catalytic material capable of successfully accelerating OH bond cleavage during the initial reaction step, but this is a difficult task. [10,11] Among electrocatalysts, noble metal platinum (Pt) is generally considered as one of the best catalysts toward HER, particularly in acidic solution, attributed to the favorable formation of Pt-H ad at active sites. [12] However, high-cost, limited reserves of elements, and sluggish reaction kinetics under alkaline conditions are also inevitable disadvantages. [13][14][15] Fortunately, research into transition non-noble metal catalytic materials has proceeded in order to obtain Pt-like performance in both acidic and alkaline conditions. [16][17][18][19][20] An excellent catalyst should have appropriate interaction with related reaction intermediate (H* for HER) based on Sabatier principle. [21] Furthermore, Nørskov et al. established a proton adsorption Gibbs free energy (∆G H* ) versus exchange current density (log(i 0 )) volcano plots, [22] in which the compound near the top of volcano has an excellent catalytic activity. According to the volcano curve, it can be judged that non-precious metal rhenium (Re) should have a good performance for HER (∆G H* = −0.56 eV, where the Pt is −0.33 eV). Regrettably, the performance of the Re is usually not satisfactory, where the overpotential is generally more than 200 mV at a current density of 10 mA cm −2 . [23] One of the main reasons is the failure to develop an effective preparation way so that the obtained metal Re maintains the nanostructure and dispersion well. [24,25] More importantly, the HER behavior of most metals including Re tends to be poorer in alkaline electrolytes than in acidic electrolytes, which is mainly due to the poor hydrophilicity and the OH bonds difficult scission. [26] Therefore, it is urgent to have a fine design of metal Re with good dispersibility and with the ability of rapid crack OH bonds of H 2 O to promote the HER.A stable Re group sulfide, rhenium disulfide (ReS 2 ) has a distorted 1T′ phase, [27] weaker interlayer spacing, [28] and anisotropic structure with a 2D morphology providing a unique electronic structure and rapid ion diffusion channels to achieve optimal catalytic performance. [29] However, the active site of such 2D materials is located at the unsaturated site of edge sulfur (S) atom, and the planes is catalytically inert for HER, [30] so their catalytic activity is still unsatisfactory. Based on this, many preparation/modification methods have been designed