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Non‐noble‐metal‐based and earth‐abundant electrocatalysts have been extensively investigated for the hydrogen evolution reaction (HER). However, they still suffer from large Tafel slopes and high overpotentials, resulting in inferior HER catalytic activity. Herein, a novel, cost‐effective, and electrochemically stable catalyst is presented by growing ultrasmall CoSe2 nanoparticles on MoS2 nanofilms using a facile hydrothermal method. The CoSe2/MoS2 hybrid catalyst shows superior catalytic activity in HER to both CoSe2 or MoS2 alone and their physical mixture. With the Tafel slope as small as 37.8 mV dec−1, the CoSe2/MoS2 shows excellent catalytic properties for HER in an acidic solution. The promising performance can be attributed to the synergistic effect of CoSe2 nanoparticles and MoS2 nanofilms. In addition, the catalytic activity of the CoSe2/MoS2 catalyst is almost unchanged after 1000 cyclic voltammetric sweeps, indicating its long‐term durability under acidic conditions. [ABSTRACT FROM AUTHOR]

Abstract: The overall electrocatalytic activity toward hydrogen evolution reaction for layered transition metal dichalcogenides is governed by their intrinsic activity, the corresponding density of active sites, and the electron transfer resistance. Here, nanoengineering strategies to scale down both the lateral size and thickness of layered 1T‐TiS2 powder to quantum dots (QDs) by bath sonication and probing sonication incision are employed. Uniform lateral size of 3–6 nm in the resulting QDs enhances the density of edge sites while the atomic layer thickness (1–2 nm) facilitates the electron transfer from the substrate to the edge sites. The obtained TiS2 QDs exhibit superior hydrogen evolution reaction activity over TiS2 nanosheets and MoS2 QDs prepared by the same method. The turnover frequency of TiS2 QDs with a small loading of 0.7 ng cm−2 in an optimal deposition on electrode reached ≈2.0 s−1 at an overpotential of −0.2 V versus RHE, several orders of magnitude higher than TiS2 nanosheets (0.01 s−1) and MoS2 QDs (0.07 s−1). [ABSTRACT FROM AUTHOR]

Photocatalysis is the most promising method for achieving artificial photosynthesis, but a bottleneck is encountered in finding materials that could efficiently promote the water splitting reaction. The nontoxicity, low cost, and versatility of photocatalysts make them especially attractive for this application. This study demonstrates that small amounts of α-Fe2O3 nanosheets can actively promote exfoliation of g-C3N4, producing 2D hybrid that exhibits tight interfaces and an all-solid-state Z-scheme junction. These nanostructured hybrids present a high H2 evolution rate >3 × 104 µmol g-1 h-1 and external quantum efficiency of 44.35% at λ = 420 nm, the highest value so far reported among the family of g-C3N4 photocatalysts. Besides effectively suppressing the recombination of electron-hole pairs, this Z-scheme junction also exhibits activity toward overall water splitting without any sacrificial donor. The proposed synthetic route for controlled production of 2D g-C3N4-based structures provides a scalable alternative toward the development of highly efficient and active photocatalysts. [ABSTRACT FROM AUTHOR]

The scarcity of inexpensive and efficient electrocatalyst for acid water oxidation to molecular oxygen presents the development of nonprecious catalysts for water oxidation a scientific priority. For water splitting, transition-metal dichalcogenides have attracted great interest as advanced catalysts for hydrogen evolution reaction, but there has been no sincere attention to generate significant anodic current density of oxygen evolution reaction (OER) with these materials. Addressing this unmet need, here, the outstanding catalytic performance of MoS2 and TaS2 in OER is demonstrated. Chemically exfoliated 2D thin sheets of MoS2 and TaS2, in both of their 1T and 2H polymorph, have been employed for OER catalysis in acid medium. The best performance for oxygen evolution, which is also comparable to benchmark IrO2, comes out from 1T-MoS2 followed by 1T-TaS2, 2H-MoS2, and 2H-TaS2. Theoretical study reveals that the dominant catalytic activity is on edge sites instead of surface and corroborates the experimental results of polymorphic dependence of electrocatalytic activity. The materials have also shown moderate durability in the harsh acidic medium. The study brings up new set of electrocatalyst for oxygen evolution in acid regime that hitherto has remained largely unrevealed. [ABSTRACT FROM AUTHOR]

Efficient separation of hole-electron pair plays a crucial role in enhancing photocatalytic water splitting activity, which essentially requires a noble metal co-catalyst. Here we report that two-dimensional (2D) metallic 1T-MoS 2 can exceed the performance of noble metal like Pt as a co-catalyst in assisting the photocatalytic hydrogen evolution over 2D semiconductor such as oxygenated monolayer graphitic carbon nitride (O-g-C 3 N 4 ). The abundance of intrinsic active site for hydrogen evolution reaction for 1T-MoS 2 partly contributes to the outstanding performance of 1T-MoS 2 /O-g-C 3 N 4 system. More importantly, the 2D heterostructure junction of 2D metals-2D semiconductor through van der Waals interaction minimizes the Schottky barrier, which in turn improves the charge transfer efficiency. The optimal 1T-MoS 2 /O-g-C 3 N 4 exhibited H 2 evolution rate as high as ∼1841.72 μmol/g/h, an external quantum efficiency of ∼7.11% at λ = 420 nm, and a super high TOF of 156.6 h −1 . [ABSTRACT FROM AUTHOR]