A simple treatment with Li-ethylenediamine alters the surface of WO3 nanoparticles with localized defects that form a thin disordered layer and modifies the electronic structure suitable for hydrogen generation.

Photocatalytic water splitting offers an economic and sustainable pathway for producing hydrogen as a zero-emission fuel, but it still suffers from low efficiencies limited by visible-light absorption capacity and charge separation kinetics. Herein, we report an interface-engineered 2D-C3N4/NiFe layered double hydroxide (CN/LDH) heterostructure that shows highly enhanced photocatalytic hydrogen evolution reaction (HER) rate with excellent long-term stability. The morphology and band gap structure of NiFe-LDH are precisely regulated by employing NH4F as a structure-directing agent, which enables a fine interfacial tuning via coupling with 2D-C3N4. The formation of a type II interface in CN/LDH enlarges the active surface area and promotes the charge separation efficiency, leading to an HER rate of 3087 μmol g–1 h–1, which is 14 times higher than that of 2D-C3N4. This study highlights a rational interface engineering strategy for the formation of a heterostructure with a proper hole transport co-catalyst for designing effective water-splitting photocatalysts.

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With excellent performance in the hydrogen evolution reaction (HER), molybdenum disulfide (MoS2) is considered a promising nonprecious candidate to substitute Pt‐based catalysts. Herein, pulsed laser irradiation in liquid is used to realize one‐step exfoliation of bulk 2H‐MoS2 to ultrastable few‐layer MoS2 nanosheets. Such prepared MoS2 nanosheets are rich in S vacancies and metallic 1T phase, which significantly contribute to the boosted catalytic HER activity. Protic solvents play a pivotal role in the production of S vacancies and 2H‐to‐1T phase transition under laser irradiation. MoS2 exfoliated in an optimal solvent of formic acid exhibits outstanding HER activity with an overpotential of 180 mV at 10 mA cm−2 and Tafel slope of 54 mV dec−1.

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High-entropy oxides (HEOs), a class of newly emerging energy conversion and storage technology materials, have gained significant interest due to their unique structure, complex stoichiometry, and corresponding synergetic effect. Despite the increasing number of reported studies related to HEOs in recent years, details of their structural properties and electrochemical activities are still lacking. Herein, the exciting developments of HEOs regarding their design, synthesis, characterization, theoretical calculations, and electrochemical performances are outlined. The fundamentals of HEOs, including their strict definition, main features, and four-core aspect effects are presented. The different synthetic methods of HEOs are categorized to highlight the significance of parameter optimization to ensure the single-phase stability of HEOs. The advances in characterization techniques on the local lattice and atomic distribution and the basic principles of combinatorial screening methods based on computational techniques are also elaborated. Recent HEO-based electrode/electrocatalysts toward Li-ion batteries and oxygen catalysis are reviewed to assess the potential applications of HEOs. This review draws attention to the critical challenges of HEOs that are worth more extensive explorations in the future.

Defect and phase engineering can effectively tune the activity of photocatalysts by altering their band structure and active site configuration. Herein, we report the phase-controlled synthesis of tungsten oxide (WO3) nanoplates via a wet-chemical approach. By adjusting the ratio of trioctylphosphine and trioctylphosphine oxide, oxygen vacancies are induced in WO3 at a relatively low temperature, accompanying the crystal structure transition from monoclinic to orthorhombic or pseudocubic phase. The experimental results and DFT calculations reveal that the increased oxygen vacant sites in WO3 lead to the upshift in both conduction band minimum and valence band maximum. The reformed band structure of reduced WO3 samples (WO3–x ) enables the photocatalytic hydrogen evolution without cocatalyst at a maximum steady rate of 340 μmol g–1 h–1 under simulated sunlight. Our work demonstrates a simple and effective strategy of introducing oxygen vacancy to WO3 for band structure tuning, which may be further extended to other metal oxide systems.

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