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Photodynamic therapy (PDT) has emerged as a promising approach for tumor treatment. However, traditional type II PDT faces limitations due to its oxygen-dependent nature. Type-I photosensitizers (PSs) exhibit superiority over conventional type-II PSs owing to their diminished oxygen dependence. Nevertheless, designing effective type-I PSs remains a significant challenge. In this work, we provide a novel strategy to tune the PDT mechanism of an excited photosensitizer through aryl substituent engineering. Using S-rhodamine as the base structure, three PSs were synthesized by incorporating phenyl, furyl, or thienyl groups at the meso position. Interestingly, furyl- or thienyl-substituted S-rhodamine are type-I-dominated PSs that produce O2˙−, while phenyl S-rhodamine results in O2˙− and 1O2 through type-I and type-II mechanisms, respectively. Experimental analyses and theoretical calculations showed that the introduction of a five-membered heterocycle at the meso position promoted intersystem crossing (ISC) and electron transfer, facilitating the production of O2˙−. Furthermore, furyl- or thienyl-substituted S-rhodamine exhibited high phototoxicity at ultralow concentrations. Thienyl-substituted S-rhodamine showed promising PDT efficacy against hypoxic solid tumors. This innovative strategy provides an alternative approach to developing new type-I PSs without the necessity for creating entirely new skeletons. [ABSTRACT FROM AUTHOR]

Nitrate (NO3‒) pollution poses significant threats to water quality and global nitrogen cycles. Alkaline electrocatalytic NO3‒ reduction reaction (NO3RR) emerges as an attractive route for enabling NO3‒ removal and sustainable ammonia (NH3) synthesis. However, it suffers from insufficient proton (H+) supply in high pH conditions, restricting NO3‒-to-NH3 activity. Herein, we propose a halogen-mediated H+ feeding strategy to enhance the alkaline NO3RR performance. Our platform achieves near-100% NH3 Faradaic efficiency (pH = 14) with a current density of 2 A cm–2 and enables an over 99% NO3–-to-NH3 conversion efficiency. We also convert NO3‒ to high-purity NH4Cl with near-unity efficiency, suggesting a practical approach to valorizing pollutants into valuable ammonia products. Theoretical simulations and in situ experiments reveal that Cl-coordination endows a shifted d-band center of Pd atoms to construct local H+-abundant environments, through arousing dangling O-H water dissociation and fast *H desorption, for *NO intermediate hydrogenation and finally effective NO3‒-to-NH3 conversion. Alkaline nitrate electroreduction to ammonia is restricted by insufficient H+ supply. Here, the authors propose a halogen-mediated H+ feeding strategy, by triggering dangling O-H water dissociation and fast *H desorption for *NO intermediate hydrogenation, to enhance the formation of ammonia. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) presents a promising approach for combating periodontitis, an infectious disease triggered by bacteria. However, the hypoxic environment within periodontal pockets poses challenges for PDT efficacy. In this study, novel purine‐based C^N ligands are utilized to develop Ir(III) complexes with enhanced reactive oxygen species (ROS) generation capacity for periodontitis treatment. The type I/II PDT performance of Ir(III) is greatly enhanced by the purine ligands, which leads to potent bactericidal and biofilm elimination efficacy. In a rat model of periodontitis, local application of these purine‐based Ir(III) complexes effectively achieves antibacterial and anti‐inflammatory effects while promoting tissue repair under clinical luminaire exposure. This PDT strategy utilizing purine‐based Ir(III) complexes circumvents the need for antibiotics and surgical intervention, emerging as a promising, non‐invasive approach for managing periodontitis. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) present substantial potential in electrocatalytic CO 2 reduction reactions; however, inferior accessibility of single-atom sites to CO 2 limits the overall CO 2 RR performances. Herein, we propose to improve the accessibility between In sites and CO 2 through the construction of a three-dimensional (3D) porous indium single-atom catalyst (In 1 /NC-3D). The NaCl template-mediated synthesis strategy generates the unique 3D porous nanostructure of In 1 /NC-3D. Multiple characterizations validate that In 1 /NC-3D exhibits increased exposure of active sites and enhanced CO 2 transport/adsorption capacity compared to the bulk In 1 /NC, thus improving accessibility of active sites to CO 2 . As a result, the In 1 /NC-3D presents superior CO 2 RR performance to the bulk In 1 /NC, with a partial current density of formate of 67.24 mA cm -2 at -1.41 V, relative to a reversible hydrogen electrode (vs RHE). The CO 2 RR performances with high formate selectivity at a large current density also outperform most reported In-based SACs. Importantly, the In 1 /NC-3D is demonstrated to maintain an FE formate of >82% at -66.83 mA·cm -2 over 21 h. This work highlights the design of a 3D porous single-atom catalyst for efficient CO 2 RR, promoting the development of advanced catalysts toward advanced energy conversion.