Hydrogen is an efficient, clean, and economical energy source, owing to its huge energy density. Electrochemical water splitting is a potential candidate for inexpensive and eco‐friendly hydrogen production. Recently, the development of 2D transition metal chalcogenides (TMDs) nanomaterials with a variety of physicochemical properties has shown their potential as eminent non‐noble metal‐based nanoscale electrocatalysts for hydrogen evolution. Nanostructuring such materials induces deep modification of their functionalities, compared to their bulk counterparts. High density of different types of exposed active sites is formed, and the small diffusion paths, which enhances the electron transfer in the 2D structures, can successfully aid the charge collection process in the electrocatalytic hydrogen evolution reactions. In this review, the key parameters to improve the catalyst performance of 2D TMDs in electrochemical hydrogen evolution reaction (HER) processes are discussed in detail and the most recent developments in the field are summarized, focusing on the improvement of the electrocatalytic activity of 2D TMDs. This review delivers deep insight for the clear understanding of the potential of 2D TMDs nanoscale materials as electrocatalysts for HER, suggesting the development of new type of catalyst with efficient activity in HER as well as other renewable energy fields.

The present article reports a facile approach to fabrication of mesoporous octahedron-shaped tricobalt tetroxide nanoparticles (Co₃O₄ NPs) with a very narrow size distribution for eco-friendly remediation of toxic dyes. Co₃O₄ NPs were fabricated by a sol–gel process using cobalt chloride hexahydrate (CoCl₂·6H₂O) and monosodium succinate (C₄H₅O₄Na) as a chelating/structure-directing agent and sodium dodecyl sulfate as a surfactant. Moreover, the phase structure, elemental composition, and thermal and morphological facets of Co₃O₄ NPs were investigated using XRD, FT-IR, EDS, Raman, XPS, TGA, SEM, and TEM techniques. The face-centered cubic spinel crystalline structure of the Co₃O₄ NPs was confirmed by XRD and SEM, and TEM analysis revealed their octahedron morphology with a smooth surface. Moreover, the narrow pore size distribution and the mesoporous nature of the Co₃O₄ NPs were confirmed by Brunauer–Emmett–Teller measurements. The photocatalytic activity of Co₃O₄ NPs for degradation of methyl red (MR), Eriochrome Black-T (EBT), bromophenol blue (BPB), and malachite green (MG) was examined under visible light irradiation, and the kinetics of the dye degradation was pseudo-zero-order with the rate constant in the order of MR > EBT > MG > BPB. Furthermore, the mechanism of photo-disintegration mechanism of the dye was examined by a scavenging test using liquid chromatography–mass chromatography, and its excellent photodegradation activities were attributed to the photogenerated holes (h⁺), superoxide (O₂^–) anions, and hydroxyl (^·OH) radicals. Finally, the synergistic effect of the nano-interconnected channels with octahedron geometry, mesoporous nature, and charge transfer properties along with photogenerated charge separations leads to an enhanced Co₃O₄ photocatalytic activity.