Photochemical conversion of CO₂ into high-value C₂₊ products is difficult to achieve due to the energetic and mechanistic challenges in forming multiple C-C bonds. Herein, an efficient photocatalyst for the conversion of CO₂ into C₃H₈ is prepared by implanting Cu single atoms on Ti_0.91O₂ atomically-thin single layers. Cu single atoms promote the formation of neighbouring oxygen vacancies (V_Os) in Ti_0.91O₂ matrix. These oxygen vacancies modulate the electronic coupling interaction between Cu atoms and adjacent Ti atoms to form a unique Cu-Ti-V_O unit in Ti_0.91O₂ matrix. A high electron-based selectivity of 64.8% for C₃H₈ (product-based selectivity of 32.4%), and 86.2% for total C₂₊ hydrocarbons (product-based selectivity of 50.2%) are achieved. Theoretical calculations suggest that Cu-Ti-V_O unit may stabilize the key *CHOCO and *CH₂OCOCO intermediates and reduce their energy levels, tuning both C₁-C₁ and C₁-C₂ couplings into thermodynamically-favourable exothermal processes. Tandem catalysis mechanism and potential reaction pathway are tentatively proposed for C₃H₈ formation, involving an overall (20e⁻ – 20H⁺) reduction and coupling of three CO₂ molecules at room temperature.

Photocatalytic hydrogen evolution from water has triggered an intensive search for metal-free semiconducting photocatalysts. However, traditional semiconducting materials suffer from limited hydrogen evolution efficiency owing to low intrinsic electron transfer, rapid recombination of photogenerated carriers, and lack of artificial microstructure. Herein, we report a metal-free half-metallic carbon nitride for highly efficient photocatalytic hydrogen evolution. The introduced half-metallic features not only effectively facilitate carrier transfer but also provide more active sites for hydrogen evolution reaction. The nanosheets incorporated into a micro grid mode resonance structure via in situ pyrolysis of ionic liquid, which show further enhanced photoelectronic coupling and entire solar energy exploitation, boosts the hydrogen evolution rate reach up to 1009 μmol g⁻¹ h⁻¹. Our findings propose a strategy for micro-structural regulations of half-metallic carbon nitride material, and meanwhile the fundamentals provide inspirations for the steering of electron transfer and solar energy absorption in electrocatalysis, photoelectrocatalysis, and photovoltaic cells.

The development of visible-light-responsive catalysts with efficient recyclability is important for solar energy conversion applications. Here, we report a three-dimensional (3D) heterohierarchical device consisting of two-dimensional (2D) p-type narrow bandgap semiconductor CuO nanosheets and one-dimensional n-type wide bandgap semiconductor ZnO nanorods that was fabricated via hydrothermal reaction after in situ crystallization on Cu foil. This heterostructured composite exhibited significantly enhanced visible light photocatalytic reduction capacity with stable recyclability to hexavalent chromium (Cr(VI)) compared with pure CuO nanosheets and ZnO nanorods. This improved photocatalysis was attributed to the synergistic actions of CuO and ZnO consisting of their formed p–n hetero-interface for the extension of solar absorption and the anti-recombination of photogenerated electron–hole pairs, demonstrating the potential for p–n heterostructures to be used for solar photocatalytic pollutant degradation or energy conversion. Moreover, the control of the photogenerated electron reservoir cultivated on ZnO nanorods over the photocatalytic reduction activity was demonstrated, further clarifying the photocarrier dynamics and the photocatalytic mechanism in the CuO–ZnO heterojunction. The preparation of the 3D CuO–ZnO p–n junction device could provide a brand new approach to design versatile devices for solar energy conversion.

The oxygen evolution reaction plays a vital role in modern energy conversion and storage, and developing cost-efficient oxygen evolution reaction catalysts with industrially relevant activity and durability is highly desired but still challenging. Here, we report an efficient and durable FeNi hydroxide organic framework nanosheet array catalyst that competently affords long-term oxygen evolution reaction at industrial-grade current densities in alkaline electrolyte. The desirable high-intensity performance is attributed to three aspects as follows. First, two-dimensional nanosheet porous arrays with maximum specific surface facilitate mass/charge transfer to accommodate high-current-density catalysis. Second, in situ derived FeNi hydroxide motifs offer bimetallic synergistic catalysis centers with high intrinsic activity. Third, carboxyl ligands alleviate metal oxidation favorable for charge tolerability against peroxidation dissolution under strong polarization. As a result, this catalyst requires an overpotential of only 280 mV to deliver high current density up to 1 A/cm² with long durability over 1000 h. Moreover, an alkaline water electrolyzer with this catalyst alternative demonstrates an increased economic effectiveness compared to commercial levels at present.