Yanjuan Sun

Photocatalytic CO2 reduction to CH4 using H2O offers a sustainable route for solar fuel production but remains challenged by the lack of non-noble-metal cocatalysts that are both efficient and selective. Herein, we report a stepwise photodeposition strategy to anchor Cu-Bi alloy sub-nanoclusters (ASNCs, 0.84 ± 0.12 nm) on blue TiO2 (BT) for CO2 photoreduction. The optimal Bi0.4Cu0.6/BT catalyst achieves a CH4 evolution rate of 94.4 μmol·g−1·h−1 with a selectivity of 96.9% under simulated solar irradiation, substantially outperforming monometallic Cu/BT and Bi/BT. The synergistic interaction between Cu and Bi can inhibit the aerial oxidation of metallic Cu0 and Bi0, accelerate the separation of photogenerated electron−hole pairs, thereby boosting CO2 adsorption and activation. Meanwhile, strong interfacial dielectric coupling between the ASNCs and BT support creates interface states (IFS), which enables visible-light-driven hot electron injection, thereby significantly enhancing the charge separation efficiency and overall photocatalytic activity. Furthermore, the Cu-Bi alloy substantially lowers the Gibbs free energy barrier for CO2 adsorption over Cu active sites and establishes a thermodynamically favorable pathway for stepwise hydrogenation of CO2 toward CH4. This work establishes a non-noble-metal alloy sub-nanocluster strategy on defect-engineered TiO2 for efficient and selective CO2-to-CH4 photoreduction.

The atmospheric chlorine radical (Cl•) is a highly reactive oxidant. However, its formation on particulate matter (PM) surfaces and its role in nitrogen chemistry remain insufficiently understood. This study investigated the Cl• chemistry on photoactive PM and evaluated its potential influence on atmospheric nitrogen cycling. Experimental evidence confirms that the chloride ion (Cl–) on the photoactive surface undergoes oxidation by photogenerated hole (h+) to form Cl•, which subsequently accelerates nitrite intermediate conversion to gaseous nitrogen oxides (NOx). Under the model experimental conditions, this process enhanced NOx formation by approximately 40-fold, while Cl– was regenerated during the reaction. Additional experiments with different chloride salts and acidity controls indicate that the enhancement is mainly associated with Cl–-involved photochemistry. This mechanism maintains efficacy across various humidity conditions and can be extended to diverse photoreactive PM (e.g., soot) and different nitrogen-containing components (e.g., ammonium, 4-nitrophenol). Experiments with reduced photoactive matter loadings and simulated atmospheric PM further reveal that the reaction rate is regulated by PM composition and the abundance of photoactive matter. Environmental simulations suggest that this surface Cl• cycling process may contribute 0.7%–6.2% to NO2 variability in the study area. Overall, this study identifies a previously overlooked Cl•-mediated surface process on photoactive PM and highlights its potential contribution to tropospheric nitrogen transformations.

Halide perovskite nanocrystals are promising photocatalysts for CO2 reduction due to their strong light absorption, defect tolerance, and tunable excited-state properties, but their practical performance remains limited by tightly bound excitons, rapid charge recombination, and inefficient interfacial electron delivery. Here, we report an anthraquinone (AQ)-modified CsPbBr3 nanocrystal photocatalyst (CPB/AQ) in which the redox-active π-conjugated AQ ligand functions as an interfacial electron relay and molecular electric-field modulator. Experimental and theoretical analyses collectively reveal that AQ creates an additional interfacial charge-transfer pathway, strengthens the light-induced surface potential difference from 170 to 270 mV, and decreases the exciton binding energy from 44.05 to 40.74 meV. Consequently, CPB/AQ achieves a CO yield of 433.50 μmol g–1 within 3 h under AM 1.5G irradiation, 4.54 times that of pristine CPB, and maintains stable CO evolution during a 25 h test. Isotopic 13CO2 tracing verifies that CO originates from CO2 reduction, while in situ FTIR spectroscopy demonstrates enhanced CO2 adsorption/activation and accelerated formation of *COOH and *CO intermediates on CPB/AQ. This work highlights molecularly gated interfacial electric-field regulation as an effective strategy for overcoming charge-transfer bottlenecks in perovskite nanocrystal photocatalysis.

CsPbBr3 perovskite nanocrystals have been investigated as photocatalysts for CO2 reduction owing to their excellent light-harvesting and multi-exciton generation. However, under strong illumination, Pb2+ migration and reduction to metallic Pb0 cause lattice collapse and accelerated carrier recombination, severely limiting their stability and photocatalytic performance. Here, we developed a dynamic valence regulation approach using Eu2+/Eu3+ redox couple to enhance lattice stability and improve photocatalytic performance by suppressing Pb2+ migration and Pb0 exsolution, modulating phonon coupling, and prolonging hot-carrier lifetimes. Experimental analyses suggest that Eu incorporation, together with mixed Eu valence states, is associated with improved lattice stability and reduced Pb-related destabilization under photocatalytic conditions. Moreover, Eu incorporation strengthens lattice rigidity and reduces electron–phonon coupling, which collectively slows down the thermalization of hot carriers. Transient absorption spectroscopy indicates a nearly 4-fold extension in hot-carrier lifetime compared to the pristine counterpart. As a result, the Eu-modified CsPbBr3 exhibits a 6-fold enhancement in CO2-to-CO conversion activity (300 ± 5 mmol·m−2) and maintains over 80% of its activity after continuous operation for 60 h. This work proposes a synergistic redox-lattice-carrier regulation mechanism, providing insights into the rational design of metal halide perovskite photocatalysts.

The catalytic reduction of nitric oxide (NO) to ammonia (NO reduction reaction (NORR)) provides a dual-benefit environmental pathway that simultaneously mitigates harmful NO emissions and supports sustainable nitrogen management. Significant advances have been made in understanding active-site structures, orbital hybridization, and proton-coupled electron-transfer steps governing NO activation and selectivity. However, most progress has been achieved under idealized laboratory conditions, whereas real flue-gas environments pose substantial challenges to catalyst stability, competitive adsorption, reaction pathways, and system integration. This review critically evaluates mechanistic insights, catalyst design principles, and emerging reactor configurations relevant to NORR under practical conditions. By integrating environmental catalysis with process engineering considerations, we outline strategies to enhance selectivity, impurity tolerance, and operational robustness. Finally, key research priorities and sustainability implications are identified to guide the advancement and deployment of NORR technologies for resource-oriented utilization of industrial flue gas NO streams.

Selective regulation of reactive oxygen species (ROS) is crucial for achieving complete mineralization of volatile organic compounds (VOCs). Here, we report the first structurally distinct ZnSnGa ternary layered double hydroxide (ZnSnGa LDH), where Ga³⁺ serves as a framework cation rather than a dopant. This unique lattice configuration weakens Ga-OH bonds and enables light-driven hydroxyl reconstruction. The resulting detach-vacancy-replenishment cycle continuously generates surface hydroxyl vacancies, exposing unsaturated Ga sites that promote p-p orbital hybridization with O₂. Consequently, O₂ is selectively activated into singlet oxygen (¹O₂), while dissociative hydroxyls are oxidized into ^•OH. In situ spectroscopy, radical trapping, and density functional theory (DFT) reveal that ¹O₂ preferentially attacks benzylic C-H bonds to trigger ring opening, whereas ^•OH accelerates intermediate oxidation. This complementary ROS synergy enables nearly complete toluene degradation (≈100%) with 99.8% mineralization efficiency, high stability (10 cycles), and, critically for practical application, broad humidity tolerance (0-100% RH). Beyond VOC abatement, this work establishes light-driven hydroxyl reconstruction as an intrinsic property of the ternary LDH lattice, offering a generalizable defect-engineering strategy for selective ROS regulation. These findings broaden the LDH compositional space and provide a framework for next-generation photocatalysts for robust environmental remediation.

Cost‐effective chemiresistive gas sensors are widely applicated in the commercial detection of volatile organic compounds (VOCs). However, their poor selectivity towards a target VOC within chemically similar mixtures impedes both qualitative and quantitative accuracy. This arises from the absence of intrinsic chemical criteria for designing selective sensing systems. This research emphasizes the importance of orbital engineering to achieve selectivity in chemiresistive materials. We tailor O 2 p ‐band center (ε _{O‑2 p} ) of the model material SnO ₂ , achieving near 100% selectivity towards triethylamine (C ₆ H ₁₅ N) and exceptional selectivity towards formaldehyde (CH ₂ O), respectively, and maintaining these selectivity performances in gas mixtures. Specifically, tailoring the ε _{O‑2 p} enables energy‐level matching between O 2 p orbitals and frontier molecular orbitals (FMOs) of distinct VOCs gases, thereby inducing selective orbital hybridizations. Such hybridization drives specific adsorption‐reaction processes and provides the electron‐transfer channel, ultimately triggering the exclusive electrical response. These findings not only unveil the origin of sensing selectivity but also establish a chemical coding strategy for the rational design of exclusive gas sensors based on an orbital‐energy‐matching framework.

Cost‐effective chemiresistive gas sensors are widely applicated in the commercial detection of volatile organic compounds (VOCs). However, their poor selectivity towards a target VOC within chemically similar mixtures impedes both qualitative and quantitative accuracy. This arises from the absence of intrinsic chemical criteria for designing selective sensing systems. This research emphasizes the importance of orbital engineering to achieve selectivity in chemiresistive materials. We tailor O 2 p ‐band center (ε _{O‑2 p} ) of the model material SnO ₂ , achieving near 100% selectivity towards triethylamine (C ₆ H ₁₅ N) and exceptional selectivity towards formaldehyde (CH ₂ O), respectively, and maintaining these selectivity performances in gas mixtures. Specifically, tailoring the ε _{O‑2 p} enables energy‐level matching between O 2 p orbitals and frontier molecular orbitals (FMOs) of distinct VOCs gases, thereby inducing selective orbital hybridizations. Such hybridization drives specific adsorption‐reaction processes and provides the electron‐transfer channel, ultimately triggering the exclusive electrical response. These findings not only unveil the origin of sensing selectivity but also establish a chemical coding strategy for the rational design of exclusive gas sensors based on an orbital‐energy‐matching framework.