The photocatalytic CO2 reduction reaction is a sustainable route to the direct conversion of greenhouse gases into chemicals without additional energy consumption. Given the vast amount of greenhouse gas, numerous efforts have been devoted to developing inorganic photocatalysts, e.g., titanium dioxide (TiO2), due to their stability, low cost, and environmentally friendly properties. However, a more efficient TiO2 photocatalyst without noble metals is highly desirable for CO2 reduction, and it is both difficult and urgent to produce selectively valuable compounds. Here, a novel “single‐atom site at the atomic step” strategy is developed by anchoring a single tungsten (W) atom site with oxygen‐coordination at the intrinsic steps of classic TiO2 nanoparticles. The composition of active sites for CO2 reduction can be controlled by tuning the additional W5+ to form W5+–O–Ti3+ sites, resulting in both significant CO2 reduction efficiency with 60.6 μmol g−1 h−1 and selectivity for methane (CH4) over carbon monoxide (CO), which exceeds those of pristine TiO2 by more than one order of magnitude. The mechanism relies on the accurate control of the single‐atom sites at step with 22.8% coverage of surface sites and the subsequent excellent electron–hole separation along with the favorable adsorption–desorption of intermediates at the sites.

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Over the past several decades, much effort has been applied to atmospheric nitrogen oxide (NOx) abatement. The current techniques require high energy consumption and result in secondary pollution. Particularly, the removal of low dose (<200 ppm) of NOx has been very challenging. Though graphitic carbon nitride (g‐CN), an eco‐friendly and sustainable material was tried as a promising metal‐free photocatalyst for NOx abatement. Herein, a one‐step, energy efficient calcination approach is developed to prepare amorphous carbon nitride (ACN) with N3C‐site vacancies. The visible‐light responsive range is expanded and the activation barrier of NO triple bonds is sharply decreased by one order of magnitude; 0.19 eV when compared to the 2.22 eV of g‐CN. These modifications allow the NOx removal efficiency of ACN to reach 57.1% which is among the highest in visible light. The unique N3C‐site vacancies are well maintained after photocatalytic NO oxidation, which shows an exceptional structural stability. This boosts the generation of singlet oxygen (1O2) and superoxide radical (•O2−) for complete NO removal. This study sheds light on the active site design and photocatalytic performance enhancement of g‐CN based materials by vacancy engineering.

Photocatalytic conversion of CO2 to high-value products plays a crucial role in the global pursuit of carbon–neutral economy. Junction photocatalysts, such as the isotype heterojunctions, offer an ideal paradigm to navigate the photocatalytic CO2 reduction reaction (CRR). Herein, we elucidate the behaviors of isotype heterojunctions toward photocatalytic CRR over a representative photocatalyst, g-C3N4. Impressively, the isotype heterojunctions possess a significantly higher efficiency for the spatial separation and transfer of photogenerated carriers than the single components. Along with the intrinsically outstanding stability, the isotype heterojunctions exhibit an exceptional and stable activity toward the CO2 photoreduction to CO. More importantly, by combining quantitative in situ technique with the first-principles modeling, we elucidate that the enhanced photoinduced charge dynamics promotes the production of key intermediates and thus the whole reaction kinetics.