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Metallic molybdenum sulfide (1T-MoS2) is considered as the most promising electrocatalyst for the acidic hydrogen evolution reaction (HER). Nevertheless, exploring a facile and effective approach for achieving high-purity 1T-MoS2 is still full of challenges. Herein, we demonstrate a two-dimensional material-assisted confined synthetic strategy, as an available method to construct and stabilize 1T-MoS2. During the hydrothermal process, the interaction between the N source and MoS2 is largely enhanced in a two-dimensional confined reactor, formed by reduced graphene oxides, successfully obtaining a high concentration of 90.1% of 1T-MoS2, named N-MoS2/rGO. The optimal N-MoS2/rGO nanosheets require a low overpotential (130 mV) to reach a current density of 10 mA·cm–2 and a low Tafel slope of 46.5 mV·dec–1. Additionally, they also exhibit high stability for at least 12 h in an acidic electrolyte maintaining 84.2% of the 1T-MoS2 phase. This work opens up an avenue to construct two-dimensional metastable materials for advanced catalysis. [ABSTRACT FROM AUTHOR]

Addressing the sluggish kinetics in the alkaline hydrogen oxidation reaction (HOR) is a pivotal yet challenging step toward the commercialization of anion-exchange membrane fuel cells (AEMFCs). Here, we have successfully immobilized indium (In) atoms in an orderly fashion into platinum (Pt) nanoparticles supported by reduced graphene oxide (denoted as O-Pt 3 In/rGO), significantly enhancing alkaline HOR kinetics. We have revealed that the ordered atomic matrix enables uniform and optimized hydrogen binding energy (HBE), hydroxyl binding energy (OHBE), and carbon monoxide binding energy (COBE) across the catalyst. With a mass activity of 2.3066 A mg -1 at an overpotential of 50 mV, over 10 times greater than that of Pt/C, the catalyst also demonstrates admirable CO resistance and stability. Importantly, the AEMFC implementing this catalyst as the anode catalyst has achieved an impressive power output compared to Pt/C. This work not only highlights the significance of constructing ordered oxophilic sites for alkaline HOR but also sheds light on the design of well-structured catalysts for energy conversion.

A strain engineering strategy is crucial for designing a high-performance catalyst. However, how to control the strain in metastable phase two-dimensional (2D) materials is technically challenging due to their nanoscale sizes. Here, we report that cerium dioxide (CeO 2 ) is an ideal loading material for tuning the in-plane strain in 2D metastable 1T-phase IrO 2 (1T-IrO 2 ) via an in situ growth method. Surprisingly, 5% CeO 2 loaded 1T-IrO 2 with 8% compressive strain achieves an overpotential of 194 mV at 10 mA cm -2 in a three-electrode system. It also retained a high current density of 900 mA cm -2 at a cell voltage of 1.8 V for a 400 h stability test in the proton-exchange membrane device. More importantly, the Fourier transform infrared measurements and density functional theory calculation reveal that the CeO 2 induced strained 1T-IrO 2 directly undergo the *O-*O radical coupling mechanism for O 2 generation, totally different from the traditional adsorbate evolution mechanism in pure 1T-IrO 2 . These findings illustrate the important role of strain engineering in paving up an optimal catalytic pathway in order to achieve robust electrochemical performance.

Electrocatalytic water splitting is a desirable and sustainable strategy for hydrogen production yet still faces challenges due to the sluggish kinetics and rapid deactivation of catalysts in the oxygen evolution process. Herein, we utilized the metal-catalyzed growth technology and phosphating process to fabricate self-supported electrodes (Co x P y @CNT-CC) composed of carbon nanotube (CNT) arrays grown on carbon cloth (CC); thereinto, cobalt-based phosphide nanoparticles (Co x P y ) are uniformly encapsulated in the cavity of the CNTs. After further optimization, when the nanoparticles are in the composite phase (CoP 2 /Co 2 P), CoP 2 /Co 2 P@CNT-CC served as catalytic electrodes with the highest activity and stability for electrocatalytic water splitting in an alkaline medium (1.0 M KOH). The as-prepared CoP 2 /Co 2 P@CNT-CC integrates the advantages of the abundant active sites and confinement effect of CNTs, imparting promising electrocatalytic activities and stability in catalyzing both hydrogen evolution reaction and oxygen evolution reaction. Remarkably, electrocatalytic water splitting cells assembled using CoP 2 /Co 2 P@CNT-CC electrodes as the cathode and anode, respectively, require a cell voltage of 1.55 V at 10 mA cm -2 , which is lower than that of the commercially noble Pt/C/CC and RuO 2 /CC catalyst couple (1.68 V). Besides, a CoP 2 /Co 2 P@CNT-CC||CoP 2 /Co 2 P@CNT-CC system shows outstanding durability for a period of 100 h at 10 mA cm -2 . This work may provide new ideas for designing bifunctional electrocatalysts for applications in electrocatalytic water splitting.