Harmonizing the cyano-group and Na to enhance selective photocatalytic O2 activation on carbon nitride for refractory pollutant degradation.

Manipulating exciton dissociation and charge-carrier transfer processes to selectively generate free radicals of more robust photocatalytic oxidation capacity for mineralizing refractory pollutants remains challenging. Herein, we propose a strategy by simultaneously introducing the cyano-group and Na into graphitic carbon nitride (CN) to obtain CN-Cy-Na, which makes the charge-carrier transfer pathways the dominant process and consequently achieves the selective generation of free radicals. Briefly, the cyano-group intensifies the local charge density of CN, offering a potential well to attract the hole of exciton, which accelerates the exciton dissociation. Meanwhile, the separated electron transfers efficiently under the robust built-in electric field induced by the cyano-group and Na, and eventually accumulates in the heptazine ring of CN for the following O2 reduction due to the reinforced electron sink effect caused by Na. As a result, CN-Cy-Na exhibits 4.42 mmol L-1 h-1 productivity with 97.6% selectivity for free radicals and achieves 82.1% total organic carbon removal efficiency in the tetracycline photodegradation within 6 h. Additionally, CN-Cy-Na also shows outstanding photodegradation efficiency of refractory pollutants, including antibiotics, pesticide plastic additives, and dyes. This work presents an innovative approach to manipulating the exciton effect and enhancing charge-carrier mobility within two-dimensional photocatalysts, opening an avenue for precise control of free radical generation.

Engineering the Coordination Environment of Ir Single Atoms with Surface Titanium Oxide Amorphization for Superior Chlorine Evolution Reaction.

The chlorine evolution reaction (CER) is essential for industrial Cl2 production but strongly relies on the use of dimensionally stable anode (DSA) with high-amount precious Ru/Ir oxide on a Ti substrate. For the purpose of sustainable development, precious metal decrement and performance improvement are highly desirable for the development of CER anodes. Herein, we demonstrate that surface titanium oxide amorphization is crucial to regulate the coordination environment of stabilized Ir single atoms for efficient and durable chlorine evolution of Ti monolithic anodes. Experimental and theoretical results revealed the formation of four-coordinated Ir1O4 and six-coordinated Ir1O6 sites on amorphous and crystalline titanium oxides, respectively. Interestingly, the Ir1O4 sites exhibited a superior CER performance, with a mass activity about 10 and 500 times those of the Ir1O6 counterpart and DSA, respectively. Moreover, the Ir1O4 anode displayed excellent durability for 200 h, far longer than that of its Ir1O6 counterpart (2 h). Mechanism studies showed that the unsaturated Ir in Ir1O4 was the active center for chlorine evolution, which was changed to the top-coordinated O in Ir1O6. This change of active sites greatly affected the adsorption energy of Cl species, thus accounting for their different CER activity. More importantly, the amorphous structure and restrained water dissociation of Ir1O4 synergistically prevent oxygen permeation across the Ti substrate, contributing to its long-term CER stability. This study sheds light on the importance of single-atom coordination structures in the reactivity of catalysts and offers a facile strategy to prepare highly active single-atom CER anodes via surface titanium oxide amorphization.

Cu1-Fe Dual Sites for Superior Neutral Ammonia Electrosynthesis from Nitrate.

The electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3 -) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3 - to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen-containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH-neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3 -. Herein, we constructed a Cu1-Fe dual-site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero-valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3 - removal efficiency of 94.8 % and NH3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L-1 NO3 --N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3 - adsorption on Fe sites and strengthened water activation on single-atom Cu sites, decreasing the energy barrier for the rate-determining step of *NO-to-*NOH. This work develops a novel strategy of fabricating dual-site catalysts to enhance the electrosynthesis of NH3 from NO3 -, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.

Size Effects of Highly Dispersed Bismuth Nanoparticles on Electrocatalytic Reduction of Carbon Dioxide to Formic Acid.

Electrocatalytic reduction of carbon dioxide into value-added chemical fuels is a promising way to achieve carbon neutrality. Bismuth-based materials have been considered as favorable electrocatalysts for converting carbon dioxide to formic acid. Moreover, size-dependent catalysis offers significant advantages in catalyzed heterogeneous chemical processes. However, the size effects of bismuth nanoparticles on formic acid production have not been fully explored. Here, we prepared Bi nanoparticles uniformly supported on porous TiO2 substrate electrocatalytic materials by in situ segregation of the Bi element from Bi4Ti3O12. The Bi-TiO2 electrocatalyst with Bi nanoparticles of 2.83 nm displays a Faradaic efficiency of greater than 90% over a wide potential range of 400 mV. Theoretical calculations have also demonstrated subtle electronic structural evolutions induced by the size variations of Bi nanoparticles, where the 2.83 nm Bi nanoparticles display the most active p-band and d-band centers to guarantee high electroactivity toward CO2RR.

Photochemical Acceleration of Ammonia Production by Pt1-Ptn-TiN Reduction and N2 Activation.

Stable metal nitrides (MN) are promising materials to fit the future "green" ammonia-hydrogen nexus. Either through catalysis or chemical looping, the reductive hydrogenation of MN to MN1-x is a necessary step to generate ammonia. However, encumbered by the formation of kinetically stable M-NH1─3 surface species, this reduction step remains challenging under mild conditions. Herein, we discovered that deleterious Ti-NH1─3 accumulation on TiN can be circumvented photochemically with supported single atoms and clusters of platinum (Pt1-Ptn) under N2-H2 conditions. The photochemistry of TiN selectively promoted Ti-NH formation, while Pt1-Ptn effectively transformed any formed Ti-NH into free ammonia. The generated ammonia was found to originate mainly from TiN reduction with a minor contribution from N2 activation. The knowledge accrued from this fundamental study could serve as a springboard for the development of MN materials for more efficient ammonia production to potentially disrupt the century-old fossil-powered Haber-Bosch process.

Oxalate-Promoted SO2 Uptake and Oxidation on Iron Minerals: Implications for Secondary Sulfate Aerosol Formation.

Mineral dust serves as a significant source of sulfate aerosols by mediating heterogeneous sulfur dioxide (SO2) oxidation in the atmosphere. Given that a considerable proportion of small organic acids are deposited onto mineral dust via long-range transportation, understanding their impact on atmospheric SO2 transformation and sulfate formation is of great importance. This study investigates the effect of oxalate on heterogeneous SO2 uptake and oxidation phenomenon by in situ FTIR, theoretical calculation, and continuous stream experiments, exploiting hematite (Fe2O3) as an environmental indicator. The results highlight the critical role of naturally deposited oxalate in mononuclear monodentate coordinating surface Fe atoms of Fe2O3 that enhances the activation of O2 for oxidizing SO2 into sulfate. Meanwhile, oxalate increases the hygroscopicity of Fe2O3, facilitating H2O dissociation into reactive hydroxyl groups and further augmenting the SO2 uptake capacity of Fe2O3. More importantly, other conventional iron minerals, such as goethite and magnetite, as well as authentic iron-containing mineral dust, exhibit similar oxalate-promoted sulfate accumulation behaviors. Our findings suggest that oxalate-assisted SO2 oxidation on iron minerals is one of the important contributors to secondary sulfate aerosols, especially during the nighttime with high relative humidity.

Triangle Cl-Ag1 -Cl Sites for Superior Photocatalytic Molecular Oxygen Activation and NO Oxidation of BiOCl.

BiOCl photocatalysis shows great promise for molecular oxygen activation and NO oxidation, but its selective transformation of NO to immobilized nitrate without toxic NO2 emission is still a great challenge, because of uncontrollable reaction intermediates and pathways. In this study, we demonstrate that the introduction of triangle Cl-Ag1 -Cl sites on a Cl-terminated, (001) facet-exposed BiOCl can selectively promote one-electron activation of reactant molecular oxygen to intermediate superoxide radicals (⋅O2 - ), and also shift the adsorption configuration of product NO3 - from the weak monodentate binding mode to a strong bidentate mode to avoid unfavorable photolysis. By simultaneously tuning intermediates and products, the Cl-Ag1 -Cl-landen BiOCl achieved >90 % NO conversion to favorable NO3 - of high selectivity (>97 %) in 10 min under visible light, with the undesired NO2 concentration below 20 ppb. Both the activity and the selectivity of Cl-Ag1 -Cl sites surpass those of BiOCl surface sites (38 % NO conversion, 67 % NO3 - selectivity) or control O-Ag1 -O sites on a benchmark photocatalyst P25 (67 % NO conversion and 87 % NO3 - selectivity). This study develops new single-atom sites for the performance enhancement of semiconductor photocatalysts, and also provides a facile pathway to manipulate the reactive oxygen species production for efficient pollutant removal.

Visible Light-Driven Conversion of Carbon-Sequestrated Seawater into Stoichiometric CO and HClO with Nitrogen-Doped BiOCl Atomic Layers.

Seawater is one of the most important CO2 sequestration media for delivering value-added chemicals/fuels and active chlorine; however, this scenario is plagued by sluggish reaction rates and poor product selectivity. Herein, we first report the synthesis of nitrogen-doped BiOCl atomic layers to directly split carbon-sequestrated natural seawater (Yellow Sea, China) into stoichiometric CO (92.8 µmol h-1 ) and HClO (83.2 µmol h-1 ) under visible light with selectivities greater than 90 %. Photoelectrons enriched on the exposed BiOCl{001} facet kinetically facilitate CO2 -to-CO reduction via surface-doped nitrogen bearing Lewis basicity. Photoholes, mainly located on the lateral facets of van der Waals gaps, promote the selective oxidation of Cl- into HClO. Sequestrated CO2 also maintains the pH of seawater at around 4.2 to prevent the alkaline earth cations from precipitating. The produced HClO can effectively kill typical bacteria in the ballast water of ocean-going cargo ships, offering a green and safe way for onsite sterilization.

An efficient and cost-effective method for the purification of human basophils.

Human basophils are terminally differentiated granulocytes that are least abundant in the peripheral blood but play important roles in allergic diseases. Studies on human basophils are limited by the high cost on the isolation of human basophils by magnetic-activated cell sorting (MACS) for negative depletion of non-basophils, followed by CD123-based positive selection of basophils. Moreover, such CD123-based purification of basophils may be limited by blocking of the binding of IL-3/anti-CD123 to the surface CD123. Here we identified SSClow CD4- CD127- HLA-DR- CRTH2high as unique markers for the identification of human basophils through stringent flow cytometric analysis of leukocytes from buffy coat. We established an efficient and cost-effective method for isolating human basophils from buffy coat based on positive magnetic selection of CRTH2+ cells followed by flow cytometric sorting of SSClow CD4- CD127- HLA-DR- CRTH2high cells. Approximately 1 to 1.5 million basophils were isolated from one buffy coat with a purity of >97%. Basophils purified by this method were viable and efficiently responded to key regulators of basophils including IL-3 and anti-IgE. This method can be used for purifying human basophils for subsequent functional studies.

Vacancy-Rich and Porous NiFe-Layered Double Hydroxide Ultrathin Nanosheets for Efficient Photocatalytic NO Oxidation and Storage.

An appealing strategy in the direction of circular chemistry and sustainable nitrogen exploitation is to efficiently convert NOx pollutants into low-toxic products and simultaneously provide crop plants with metabolic nitrogen. This study demonstrates that such a scenario can be realized by a defect- and morphology-coengineered Ni-Fe-layered double hydroxide (NiFe-LDH) comprising ultrathin nanosheets. Rich oxygen vacancies are introduced onto the NiFe-LDH surface, which facilitate charge carrier transfer and enable photocatalytic O2 activation into superoxide radicals (•O2-) under visible light. •O2- on NiFe-LDH thermodynamically oxidizes NO into nitrate with selectivity over 92%, thus suppressing dangerous NO2 emissions. By merit of abundant mesopores on NiFe-LDH ultrathin nanosheets bearing a high surface area (103.08 m2/g), nitrate can be readily stored without compromising the NO oxidation reactivity or selectivity for long-term usage. The nitrate species can be easily washed off the NiFe-LDH surface and then enriched in the liquid form as easy-to-use chemicals.

Oxygen and Chlorine Dual Vacancies Enable Photocatalytic O2 Dissociation into Monatomic Reactive Oxygen on BiOCl for Refractory Aromatic Pollutant Removal.

Room-temperature molecular oxygen (O2) dissociation is challenging toward chemical reactions due to its triplet ground-state and spin-forbidden characteristic. Herein, we demonstrate that BiOCl of oxygen and chlorine dual vacancies can photocatalytically dissociate O2 into monatomic reactive oxygen (•O-) for the ring opening of aromatic refractory pollutants toward deep oxidation. The electron-rich and geometry-flexible dual vacancies of oxygen and chlorine remarkably lengthen the O-O bond of adsorbed O2 from 1.21 to 2.74 Å, resulting in the rapid O2 dissociation and the subsequent •O- formation. During the photocatalytic degradation of sulfamethazine, the in situ-formed •O- plays an indispensable role in breaking the critical intermediate of pyrimidine containing a stubborn aromatic heterocyclic ring, thus facilitating the overall mineralization. More importantly, BiOCl of oxygen and chlorine dual vacancies is also superior to its monovacancy counterparts on the degradation of other refractory pollutants containing conjugated six-membered rings, including p-chlorophenol, p-chloronitrobenzene, p-hydroxybenzoic acid, and p-nitrobenzoic acid. This study sheds light on the importance of sophisticated defects for regulating the O2 activation manner and deliveries a novel O2 activation approach for environmental remediation with solar energy.

Surface Boronizing Can Weaken the Excitonic Effects of BiOBr Nanosheets for Efficient O2 Activation and Selective NO Oxidation under Visible Light Irradiation.

The photocatalytic O2 activation for pollutant removal highly depends on the controlled generation of desired reactive oxygen species (ROS). Herein, we demonstrate that the robust excitonic effect of BiOBr nanosheets, which is prototypical for singlet oxygen (1O2) production to partially oxidize NO into a more toxic intermediate NO2, can be weakened by surface boronizing via inducing a staggered band alignment from the surface to the bulk and simultaneously generating more surface oxygen vacancy (VO). The staggered band alignment destabilizes excitons and facilitates their dissociation into charge carriers, while surface VO traps electrons and efficiently activates O2 into a superoxide radical (•O2-) via a one-electron-transfer pathway. Different from 1O2, •O2- enables the complete oxidation of NO into nitrate with high selectivity that is more desirable for safe indoor NO remediation under visible light irradiation. This study provides a facile excitonic effect manipulating method for layered two-dimensional photocatalysts and sheds light on the importance of managing ROS production for efficient pollutant removal.

[Research Progress in Regulation of Allergic Diseases by Short-Chain Fatty Acids].

Gut microbiota-derived metabolites play vital roles in the regulation of host-gut microbiota mutualism, gut homeostasis and the pathogenesis of multiple human diseases. Fermentation of indigestible dietary fibers by gut microbiota produces a variety of short-chain fatty acids (SCFAs) consisting mainly of acetate, propionate and butyrate. Despite high concentrations of SCFAs in the gut, it has been reported in a large number of studies that SCFAs are involved in the onset and development of multiple diseases, including colitis, diabetes mellitus, hepatic steatosis, and obesity. Recent studies including our work found that SCFAs regulates allergic immune reactions and the pathogenesis of allergic diseases via their action on allergic effector immune cells, including T helper 2 (Th2) cells, type 2 innate lymphoid cells (ILC2), eosinophils, mast cells and basophils. Herein, we reviewed the association of SCFAs with human allergic diseases, their role in regulating the animal model of allergic diseases and the effects of different SCFAs in regulating the functions of allergic effectors cells and the underlying mechanisms, aiming to provide research clues for in-depth investigation in the role played by SCFAs in regulating various allergic diseases.

Atomic-Layered Cu5 Nanoclusters on FeS2 with Dual Catalytic Sites for Efficient and Selective H2 O2 Activation.

Regulating the distribution of reactive oxygen species generated from H2 O2 activation is the prerequisite to ensuring the efficient and safe use of H2 O2 in the chemistry and life science fields. Herein, we demonstrate that constructing a dual Cu-Fe site through the self-assembly of single-atomic-layered Cu5 nanoclusters onto a FeS2 surface achieves selective H2 O2 activation with high efficiency. Unlike its unitary Cu or Fe counterpart, the dual Cu-Fe sites residing at the perimeter zone of the Cu5 /FeS2 interface facilitate H2 O2 adsorption and barrierless decomposition into ⋅OH via forming a bridging Cu-O-O-Fe complex. The robust in situ formation of ⋅OH governed by this atomic-layered catalyst enables the effective oxidation of several refractory toxic pollutants across a broad pH range, including alachlor, sulfadimidine, p-nitrobenzoic acid, p-chlorophenol, p-chloronitrobenzene. This work highlights the concept of building a dual catalytic site in manipulating selective H2 O2 activation on the surface molecular level towards efficient environmental control and beyond.

Induction of the apoptosis, degranulation and IL-13 production of human basophils by butyrate and propionate via suppression of histone deacetylation.

Allergic diseases are caused by dysregulated Th2 immune responses involving multiple effector cells including basophils. Short chain fatty acids (SCFAs), mainly acetate, propionate and butyrate, exert immunomodulatory functions via activation of its receptors GPR41 and GPR43, and inhibition of the histone deacetylases (HDACs) activity. In allergic diseases, SCFAs suppress the activity of mast cells, eosinophils and type 2 innate lymphoid cells (ILC2) but enhance the function of Th2 cells. Here, we aimed to elucidate the function of SCFAs on human basophils. Human basophils were purified from healthy donors by flow cytometric sorting. The surface proteins, apoptosis and degranulation of basophils were analyzed by flow cytometric analysis. The mRNA expression was assayed using real-time PCR. Interleukin 4 (IL-4) and IL-13 were measured by ELISA. Histone acetylation was examined by western blot. GPR41 was expressed by basophils and was enhanced by IL-3. Acetate induced intracellular calcium influx in basophils which was suppressed by blocking GPR41. Propionate and butyrate, but not acetate, induced the expression of CD69 and IL-13. In addition, propionate and butyrate enhanced IgE-mediated basophil degranulation but inhibited basophil survival and IL-4 secretion. Propionate and butyrate induced histone acetylation of basophils and suppression of HDACs activity mimicked the effects of propionate and butyrate on human basophils. Our findings demonstrate that propionate and butyrate may play a complex role in regulating basophil apoptosis, activation and degranulation via inhibiting HDACs activity. The in vivo effects of SCFAs on the regulation of basophil-associated allergic diseases need to be further explored.

Efficient Ammonia Electrosynthesis from Nitrate on Strained Ruthenium Nanoclusters.

The limitations of the Haber-Bosch reaction, particularly high-temperature operation, have ignited new interests in low-temperature ammonia-synthesis scenarios. Ambient N2 electroreduction is a compelling alternative but is impeded by a low ammonia production rate (mostly <10 mmol gcat-1 h-1), a small partial current density (<1 mA cm-2), and a high-selectivity hydrogen-evolving side reaction. Herein, we report that room-temperature nitrate electroreduction catalyzed by strained ruthenium nanoclusters generates ammonia at a higher rate (5.56 mol gcat-1 h-1) than the Haber-Bosch process. The primary contributor to such performance is hydrogen radicals, which are generated by suppressing hydrogen-hydrogen dimerization during water splitting enabled by the tensile lattice strains. The radicals expedite nitrate-to-ammonia conversion by hydrogenating intermediates of the rate-limiting steps at lower kinetic barriers. The strained nanostructures can maintain nearly 100% ammonia-evolving selectivity at >120 mA cm-2 current densities for 100 h due to the robust subsurface Ru-O coordination. These findings highlight the potential of nitrate electroreduction in real-world, low-temperature ammonia synthesis.

Interleukin 3-induced GITR promotes the activation of human basophils.

Human basophils regulate allergic reactions by secreting histamine, interleukin 4 (IL-4) and IL-13 through key surface receptors FcεRI as well as IL-3R, which are constitutively expressed on basophils. IL-3/IL-3R signaling axis plays key roles in regulating the development and activation of basophils. We and others have shown that IL-3-induced surface receptors e.g. ST2, IL-17RB and IL-2 receptors regulate the biology of basophils. However, the expression and function of IL-3-induced surface proteins on human basophils remain to be elucidated. We in this study aimed to identify new basophil activation regulators by transcriptomic analysis of IL-3-stimulated basophils. Gene expression microarray analysis of IL-3-treated basophils revealed 2050 differentially expressed genes, of which 323 genes encoded surface proteins including GITR. We identified that GITR was preferentially induced by IL-3 rather than anti-IgE, IL-33, fMLP and C5a. IL-3-induced GITR was suppressed by inhibitors targeting JAK2, PI3K and MEK1/2. Stimulation of IL-3-treated basophils by GITR enhanced the expression of IL-4 and IL-13. Moreover, IgE-mediated degranulation was enhanced by GITRL in the presence of IL-3. This transcriptomic analysis of IL-3-activated basophils helps to identify novel activation regulator. IL-3-induced GITR promoted the activation of basophils, adding new evidence supporting GITR as an important player in Th2-associated immune responses.

Highly selective urea electrooxidation coupled with efficient hydrogen evolution.

Electrochemical urea oxidation offers a sustainable avenue for H2 production and wastewater denitrification within the water-energy nexus; however, its wide application is limited by detrimental cyanate or nitrite production instead of innocuous N2. Herein we demonstrate that atomically isolated asymmetric Ni-O-Ti sites on Ti foam anode achieve a N2 selectivity of 99%, surpassing the connected symmetric Ni-O-Ni counterparts in documented Ni-based electrocatalysts with N2 selectivity below 55%, and also deliver a H2 evolution rate of 22.0 mL h-1 when coupled to a Pt counter cathode under 213 mA cm-2 at 1.40 VRHE. These asymmetric sites, featuring oxygenophilic Ti adjacent to Ni, favor interaction with the carbonyl over amino groups in urea, thus preventing premature resonant C⎓N bond breakage before intramolecular N-N coupling towards N2 evolution. A prototype device powered by a commercial Si photovoltaic cell is further developed for solar-powered on-site urine processing and decentralized H2 production.

Oxalated zero valent iron enables highly efficient heterogeneous Fenton reaction by self-adapting pH and accelerating proton cycle.

Heterogeneous Fenton reactions of zero-valent iron (ZVI) requires the sufficient release of Fe(II) to catalyze the H2O2 decomposition. However, the rate-limiting step of proton transfer through the passivation layer of ZVI restricted the Fe(II) release via Fe0 core corrosion. Herein we modified the shell of ZVI with highly proton-conductive FeC2O4·2H2O by ball-milling (OA-ZVIbm), and demonstrated its high heterogeneous Fenton performance of thiamphenicol (TAP) removal, with 500 times enhancement of the rate constant. More importantly, the OA-ZVIbm/H2O2 showed little attenuation of the Fenton activity during 13 successive cycles, and was applicable across a wide pH range of 3.5-9.5. Interestingly, the OA-ZVIbm/H2O2 reaction showed pH self-adapting ability, which initially reduced and then sustained the solution pH in the range of 3.5-5.2. The abundant intrinsic surface Fe(II) of OA-ZVIbm (45.54% vs. 27.52% in ZVIbm, according to Fe 2p XPS profiles) was oxidized by H2O2 and hydrolyzed to generate protons, and the FeC2O4·2H2O shell favored the fast transfer of protons to inner Fe0, therefore, the consumption-regeneration cycle of protons were accelerated to drove the production of Fe(II) for Fenton reactions, demonstrated by the more prominent H2 evolution and nearly 100% H2O2 decomposition by OA-ZVIbm. Furthermore, the FeC2O4·2H2O shell was stable and slightly decreased from 1.9% to 1.7% after the Fenton reaction. This study clarified the significance of proton transfer on the reactivity of ZVI, and provided an efficient strategy to achieve the highly efficient and robust heterogeneous Fenton reaction of ZVI for pollution control.

Locally Asymmetric BiOBr for Efficient Exciton Dissociation and Selective O2 Activation toward Oxidative Coupling of Amines.

Two-dimensional (2D) layered photocatalysts with highly ordered out-of-plane symmetry usually display robust excitonic effects, thus being ineffective in driving catalytic reactions that necessitate unchained charge carriers. Herein, taking 2D BiOBr as a prototype model, we implement a superficial asymmetric [Br-Bi-O-Bi] stacking in the out-of-plane direction by selectively stripping off the top-layer Br of BiOBr. This local asymmetry disrupts the diagnostic confinement configuration of BiOBr to urge energetic exciton dissociation into charge carriers and further contributes to the emergence of a surface dipole field that powers the subsequent separation of transient electron-hole pairs. Distinct from the symmetric BiOBr, which activates O2 into 1O2 via an exciton-mediated energy transfer, surface asymmetric BiOBr favors selective O2 activation into ·O2- for a broad range of amine-to-imine conversions. Our work here not only presents a paradigm for asymmetric photocatalyst design but also expands the toolkit available for regulating exciton behaviors in semiconductor photocatalytic systems.