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Advanced oxidation processes employing peroxymonosulfate (PMS) show significant promise for wastewater treatment. However, PMS activation typically relies on energy- and chemically intensive techniques due to its relatively low reactivity. Hence, the exploration of novel and energy-efficient approaches, such as the piezoelectric effect, for PMS activation is of paramount importance. Herein, we prepared a piezoelectric material (CoMn2O4) via a simple hydrothermal method followed by calcination. The degradation experiments of tetracycline (TC) demonstrated that CoMn2O4exhibited excellent performance under ultrasound, the apparent rate constant kis 0.191 min–1, and its degradation rate reached 83.63% after 10 min. Piezo force microscopy (PFM) tests confirmed that CoMn2O4exhibited a piezotronic effect under ultrasound. In situelectron paramagnetic resonance (in situEPR) tests revealed that PMS could be activated to form hydroxyl radicals (•OH) and sulfate radicals (SO4•–) under ultrasound, which are active species for TC degradation. Consequently, CoMn2O4effectively activated PMS into •OH and SO4•–active species, enabling the effective TC degradation. Moreover, biotoxicity experiments using germination tests showed that CoMn2O4was capable of effectively degrading TC, thereby reducing environmental toxicity. This work not only provides mechanistic insights into piezoelectric material-activated PMS for pollutants degradation but also establishes a basis for the application of piezoelectric materials in pollutant degradation.

The incorporation of nitrogen into carbon materials is a strategy that effectively boosts their catalytic potency. Herein, a nitrogen-enriched carbon substance, designated as CN0.6, was synthesized from melamine, serving as a precursor. This substance has been established to act as an efficient catalyst devoid of metals for the activation of peroxymonosulfate (PMS). At a temperature of 25 °C, a concentration of 0.05 g/L CN0.6along with 1 mM PMS suffices to achieve the complete degradation of concentrated tetracycline hydrochloride (TC) in a short period of 4 min. This enhanced catalytic performance is attributed to the optimal level of nitrogen doping, which elevates the pyrrolic nitrogen content and introduces additional defects characterized by an ID/IGratio of 1.02. These factors collectively augment the adsorptive capacity for PMS and create a greater number of active sites to facilitate its activation. The dominance of a nonradical electron transfer mechanism in the CN0.6/PMS system has been confirmed through a series of analyses, including radical identification, quenching tests, and electrochemical assessments. Employing high-resolution liquid chromatography coupled with tandem mass spectrometry (LC-MS), the investigation identified three potential degradation routes for TC. Furthermore, the intermediates produced are determined to possess reduced toxicity in comparison to TC. The findings of this study offer a approach to the synthesis of highly efficient nitrogen-doped, metal-free catalysts, presenting a promising strategy for the degradation of environmental pollutants.

We prepared BiOCl, BiO(ClBr), BiO(ClBrI), and BiO[ClBrI(CO3)0.5] materials using a simple coprecipitation method. It was found that adjusting the number of anions in the anion layer was conducive to adjusting the band structure of BiOX and could effectively promote the migration and separation of photogenerated carriers, thus improving the photocatalytic activity. We first selected methyl orange (MO) as the study pollutant and compared it with BiOCl, BiO(ClBr), and BiO(ClBrI). The first-order kinetic constants of MO degradation by BiO[ClBrI(CO3)0.5] increased by 90.3, 33.9, and 3.1 times, respectively. The photocatalytic degradation rate of methylene blue by BiO[ClBrI(CO3)0.5] was 89.5%, indicating the excellent photocatalytic performance of BiO[ClBrI(CO3)0.5]. The stability of BiO[ClBrI(CO3)0.5] was demonstrated through cyclic experiments and XRD analysis before and after the reaction. The photocatalytic degradation of MO by BiO[ClBrI(CO3)0.5] showed that h+and 1O2were the main active oxidizing species and •O2–was the secondary active substance. Overall, our work provides new ideas for the synthesis and degradation of organic pollutants by using two-dimensional anionic high-entropy materials.

Surface oxygen and metal defects can promote the performance of photocatalysts significantly, but their role in the activation of hydrogen peroxide (H2O2) for pollutant degradation is not clear. Herein, the surface oxygen vacancies (VO) and vanadium vacancies (VV: V4+/V5+) of InVO4catalysts were adjusted using different surfactants. Among them, a cationic surfactant with a hydrophilic head of quaternary ammonium ions facilitated the formation of surface vanadium vacancies (V4+/V5+) on the InVO4crystal. This VV-dominated InVO4exhibited the optimal degradation rate of rhodamine B and microcystin-LR (MC-LR) with H2O2(0.045 M) at neutral pH under visible-light irradiation, which was ∼8.2-times versus3.2-times larger than that of the Vo-dominated InVO4system. The cycle of V4+/V5+decomposed H2O2to yield hydroxyl radicals (·OH) and superoxide radicals (·O2−) continuously, which degraded organic pollutants efficiently. This study provides insights into the primary role of the V4+/V5+cycle in InVO4catalysts for promoting the photo-Fenton reaction viaadjuration of surfactants.

Restrained by the uncontrollable cleavage process of chemical bonds in methane molecules and corresponding formed intermediates, the target product in the reaction of methane selective oxidation to methanol would suffer from an inevitable overoxidation process, which is considered to be one of the most challenging issues in the field of catalysis. Herein, we report a conceptually different method for modulating the conversion pathway of methane through the selective cleavage of chemical bonds in the key intermediates to suppress the generation of peroxidation products. Taking metal oxides, typical semiconductors in the field of methane oxidation as model catalysts, we confirm that the cleavage of different chemical bonds in CH3O* intermediates could greatly affect the conversion pathway of methane, which has a vital role in product selectivity. Specifically, it is revealed that the formation of peroxidation products could be significantly prevented by the selective cleavage of C–O bonds in CH3O* intermediates instead of metal–O bonds, which is proved by the combination of density functional theory calculations and in situ infrared spectroscopy based on isotope labeling. By manipulating the lattice oxygen mobility of metal oxides, the electrons transferring from the surface to the CH3O* intermediates could directionally inject into the antibonding orbitals of the C–O bond, resulting in its selective cleavage. As a result, the gallium oxide with low lattice oxygen mobility shows a 3.8% conversion rate for methane with a high methanol generation rate (∼325.4 μmol g–1h–1) and selectivity (∼87.0%) under room temperature and atmospheric pressure in the absence of extra oxidants, which is superior among the reported studies (reaction pressure: <20 bar).

The discovery of valid catalytically active species in a catalytic system contributes to a more comprehensive understanding of the catalytic process and may improve its efficiency. Iron oxychloride (FeOCl) has been reported as an excellent novel Fenton-like catalyst. However, the nature of its outstanding activity remains highly uncertain. Herein, we clearly elucidate that FeOCl involves a homogeneous iron species in the Fenton and photo-Fenton processes, which plays a significant role in the reaction. It is also emphasized that the interaction of FeOCl with water is closely related to the dissolution of iron. Importantly, neglecting the acidic environment created by FeOCl when evaluating the contribution of dissolved iron-induced homogeneous reactions is a crucial reason for underestimating the homogeneous reactions. Hence, FeOCl can be considered a precatalyst for slow transformation in a homogeneous Fenton catalyst. This study contributes to the first insight into the role of dissolved iron in FeOCl-based AOP and suggests an extension of the role of structural features of FeOCl in catalytic processes.

With the benefits of low cost, energy efficiency, and environmental protection, photocatalytic hydrogen production is considered to be the most promising technology for the development of a clean and sustainable society. However, the utilization of photocatalytically generated hydrogen is not very common yet. Therefore, tertiary education urgently needs to guide undergraduate/graduate students to realize that the hydrogen generated by photocatalysis can be feasibly utilized. Herein, we report an experiment demonstrating the generation, storage, conversion, and utilization of photocatalytic hydrogen. In this paper, TiO2, Pt, and lactic acid are respectively used as the photocatalyst, cocatalyst, and sacrificial reagent to generate hydrogen fuel from water. Upon light illumination, hydrogen is photocatalytically produced in the TiO2–Pt–lactic acid–water system. Then, through a drainage method, the hydrogen gas is stored in a U-shaped manifold. Subsequently, the produced hydrogen is directly circulated without purification into a hydrogen fuel cell. The electricity obtained from this fuel cell is used to drive an electric fan. The total lab time is about 3 h. Upon the completion of the experiment, students can master several basic operational skills and can experience how interdisciplinary knowledge of the chemistry and physics of materials can be utilized to solve some energy and environmental problems.

Vanadium-based catalysts are considered the most promising materials to replace cobalt-based catalysts for the activation of peroxymonosulfate (PMS) to degrade organic pollutants. However, these traditional vanadium species easily leak out metal ions that can affect the environment, even though the of vanadium is much less than that of cobalt. Compared to other vanadium-based catalysts, e.g., V2O3, fluorinated V2AlC shows a high and constant activity and reusability regarding PMS activation. Furthermore, it features extremely low ion leakage. Active oxygen species scavenging and electron spin resonance measurements reveal that the main reactive oxygen species was 1O2, which was induced by a two-dimensional confinement effect. More importantly, for the real-life application of tetracycline (TC) degradation, the introduction of fluorine changed the adsorption mode of TC over the catalyst, thereby changing the degradation path. The intermediate products were detected by liquid-chromatography mass spectroscopy (LC-MS), and a possible degradation path was proposed. The environmental impact test of the decomposition products showed that the toxicity of the degradation intermediates was greatly reduced. Therefore, the investigated ultradurable catalyst material provides a basis for the practical application of advanced PMS oxidation technology.

Solar-energy-driven catalytic CO2reduction for the production of value-added carbon-based materials and chemical raw materials has attracted great interest to alleviate the global climate change and energy crisis. The production of multicarbon (C2) products through CO2reduction is extremely attractive, however, the yield and selectivity of C2 products remain low because of the low reaction temperature required and the low photoelectron density of the substrate. Here, we introduce WO3–x, which contains oxygen vacancies and exhibits an excellent photothermal conversion efficiency, to improve the generation of C2 products (C2H4and C2H6) under simulated sunlight (UV-Vis-IR) irradiation. WO3–xproduced 5.30 and 0.93 μmol·g–1C2H4and C2H6, respectively, after 4 h, with a selectivity exceeding 34%. In situFourier transform infrared spectra and theoretical calculations showed that the oxygen vacancies enhanced the water activation and hydrogenation of adsorbed CO for the formation of C2 products viaC–C coupling from CH2/CH3intermediates. The findings of this study could assist in the design of highly active solar-energy-driven catalysts to produce C–C coupling products through CO2reduction.

It is well known that graphite-like carbon nitride (g-C3N4) is a good photocatalyst for in-situ the production of H2O2. However, how to activate H2O2generating the strong oxidizing ·OH is the key factor to affect the degradation of pollutants. In this paper, the layered g-C3N4nanosheets were prepared by using urea and H2O with different mass ratios and calcined in Muffle furnace by one-step synthesis method. The morphology, composition and structure of photocatalysts were analyzed, indicating that the as-prepared L-g-C3N4-7 had abundant edge regions in comparison with L-g-C3N4made by solid urea. The photocatalytic performance of g-C3N4nanosheets was investigated with atrazine (ATZ) as the target pollutant in water. The results revealed that the prepared L-g-C3N4-7 exhibited the best photocatalytic activity in visible light (λ ≥ 420 nm). The degradation of 1.0 mg/L ATZ reached over 96% after 3 hours and the photocatalytic degradation rate constant (k) was 6.8 times than that of L-g-C3N4photocatalyst. In addition, under the same conditions, the H2O2production of L-g-C3N4-7 was 4.5 times than that of L-g-C3N4photocatalyst. Based on the capture experiments of free radicals, it was found that the contribution rate of ·OH in L-g-C3N4-7 photocatalytic increased to 17 % compared to 4 % of L-g-C3N4photocatalyst during the degradation of ATZ. The ·OH quantitative experiment indicated that the L-g-C3N4-7 photocatalyst could obviously activate H2O2to generate ·OH and the amount of ·OH was 2.5 times than that of the L-g-C3N4photocatalyst. More importantly, a large amount of terminal-NHx(14.6 %) in L-g-C3N4-7 was measured by the XPS, FT-IR and zeta potential. The additive H2O2adsorption experiment in the dark was used to confirm terminal-NHxsites of L-g-C3N4-7 photocatalyst, which was beneficial to adsorb and activate H2O2. The results illustrated that the L-g-C3N4-7 photocatalyst with rich edge regions and terminal-NHxhad the characteristics of in-situ the activation of H2O2to generate ·OH. The findings suggest that designing and developing efficient g-C3N4photocatalysts pave a new avenue for activating in situ self-synthesizing H2O2and the removal of atrazine in water.

As an efficient green water disinfection technology, photothermal synergy sterilization has been paid more attention in recent years with its immeasurable advantages. The development of photocatalysts for efficient sterilization is currently an urgent need. In this manuscript, pure Ti3C2Txis first studied as a photothermal synergy sterilization material and shows an excellent sterilization effect. The sterilization rate of Escherichia coli(E. coli) reaches 99.9% under visible infrared (vis-IR) light for 40 minutes. The peeling of the Al layer from Ti3AlC2is the fundamental reason for improving the photothermal conversion ability, and photogenerated free radicals have also proved to be improved. The dilution spreading plate method, enzyme activity test, and leakage of cell contents confirmed the complete death of bacteria. Two aspects, photogenerated free radicals and photothermal synergy, were carried to illuminate the mechanism.

In this paper, the photocatalytic activity of industrial titanium dioxide (TiO2) based nacreous pigments was researched as functional building materials for photocatalytic NO remove. Three industrial TiO2based nacreous pigments were selected to estimate the photocatalytic activity for NO remove. This study is a good proof that pearlescent pigments can eliminate NO, and its performance is positively correlated with its titanium dioxide content. And this research will widen the application of nacreous pigments in functional building materials, and provide a new way to eliminate in door nitric oxide pollution.

To improve the photocatalytic oxidation reaction activity for NO removal, photocatalysts with excellent activity are required to activate molecular oxygen. Solid solution and heterojunction were suggested as effective strategies to enhance the molecular oxygen activation viaexciton and carrier photocatalysis. In this study, a solid solution and heterojunction containing BiOBr0.5I0.5/BiOI catalyst was synthesized, and it showed improved photocatalytic activity for removing NO. The photocatalytic NO removal mechanism indicated that synergistic effects between the solid solution and heterojunction induced the enhanced activity for molecular oxygen activation. The photogenerated holes, superoxide, and singlet oxygen generated by the carrier and exciton photocatalysis supported the high photocatalytic NO removal efficiency. This study provides new ideas for designing efficient Bi-O-X(X= Cl, Br, I) photocatalysts for oxidation reactions.

The synergistic effect of Ag0/Ag+is achieved to improve the photocatalytic performance. The Ag0can be regarded as the reduction reaction sites and significantly promote the adsorption of H2O to produce more •OH radicals. While the Ag+species can enhance the adsorption of CH4and be regarded as the oxidation reaction sites.

The application of photocatalytic sterilization technology for the sterilization of water has been broadly studied in recent years. However, developing photocatalysts with high disinfection efficiency remains an urgent challenge. Tungsten trioxide with coexisting oxygen vacancies and carbon coating (WO3–x/C) has been successfully synthesized toward the photothermal inactivation of Escherichia coli. Oxygen vacancies and carbon coating bring WO3–x/C strong absorption in the infrared region and enhance the carrier separation efficiency. As a result, a higher sterilization rate is obtained compared to WO3. WO3–x/C can completely inactivate E. coliunder infrared light within 40 min through photothermal synergy process. During the process of inactivating bacteria over WO3–x/C, E. coliis killed by the destruction of their cell membrane to decrease the activity of enzymes and release the cell contents, which can be ascribed to the efficient generation of reactive oxygen species (O2•–and •OH) and thermal effect. This work demonstrates a novel approach for engineering efficient and energy-saving catalysts for water sterilization.

Limited by the chemical inertness of CO2and the high dissociation energy of the C═O bond, photocatalytic CO2conversion is highly challenging. Herein, we prepare ultrathin oxygen-modified h-BN (O/BN) nanosheets containing B–O bonds. On the O/BN surface, CO2can be chemically captured and is bonded with the B–O bond, leading to the formation of an O–B–O bond. This new chemical bond acting as an electron-delivery channel strengthens the interaction between CO2and the surface. Thus, the reactants can continuously obtain electrons from the surface through this channel. Therefore, the majority of gaseous CO2directly converts into carbon active species that are detected by in situ DRIFTS over O/BN. Moreover, the activated energies of CO2conversion are significantly reduced with the introduction of the B–O bond evidenced by DFT calculations. As a result, O/BN nanosheets present an enhanced photocatalytic CO2conversion performance with the H2and CO generation rates of 3.3 and 12.5 μmol g–1h–1, respectively. This work could help in realizing the effects of nonmetal chemical bonds in the CO2photoreduction reaction for designing efficient photocatalysts.

Fast recombination of photogenerated charge carriers in bulk remains the major obstacle for photocatalysis nowadays. Developing ferroelectrics directly as photoactive semiconducting catalysts may be promising in view of the strong ferroelectric polarization that induces the anisotropic charge separation. Here, we report a ferroelectric layered perovskite SrBi4Ti4O15as a robust photocatalyst for efficient CO2reduction. In the absence of co-catalysts and sacrificial agents, the annealed SrBi4Ti4O15nanosheets with the strongest ferroelectricity cast a prominent photocatalytic CO2reduction activity for CH4evolution with a rate of 19.8 μmol h−1g−1in the gas-solid reaction system, achieving an apparent quantum yield (AQY) of 1.33% at 365 nm, outperforming most of the reported photocatalysts. The ferroelectric hysteresis loop, piezoresponse force microscopy (PFM) and ns-level time-resolved fluorescence spectra uncover that the outstanding CO2photoreduction activity of SrBi4Ti4O15mainly stems from the strong ferroelectric spontaneous polarization along [100] direction, which allows efficient bulk charge separation along opposite direction. DFT calculations also disclose that both electrons and holes show the smallest effective masses along aaxis, verifying the high mobility of charge carriers facilitated by ferroelectric polarization. This study suggests that the traditionally semiconducting ferroelectric materials that have long been studied as ferro/piezoelectric ceramics now may be powerfully applied in the photocatalytic field to deal with the growing energy crisis.

Elaborating the specific reactive oxygen species (ROS) involved in the photocatalytic degradation of atrazine (ATZ) is of great significance for elucidating the underlying mechanism. This study provided conclusive evidence that hydroxyl radicals (·OH) were the primary ROS responsible for the efficient photocatalytic degradation of ATZ, thereby questioning the reliability of widely adopted radical quenching techniques in discerning authentic ROS species. As an illustration, oxygen-modified g-C3N4(OCN) was prepared to counteract the limitations of pristine g-C3N4(CN). Comparative assessments between CN and OCN revealed a remarkable 10.44-fold improvement in the photocatalytic degradation of ATZ by OCN. This enhancement was ascribed to the increased content of C–O functional groups on the surface of the OCN, which facilitated the conversion of superoxide radicals (·O2–) into hydrogen peroxide (H2O2), subsequently leading to the generation of ·OH. The increased production of ·OH contributed to the efficient dealkylation, dechlorination, and hydroxylation of ATZ. Furthermore, toxicity assessments revealed a significant reduction in ATZ toxicity following its photocatalytic degradation by OCN. This study sheds light on the intricate interconversion of ROS and offers valuable mechanistic insights into the photocatalytic degradation of ATZ.

Excitonic effects significantly influence the selective generation of reactive oxygen species and photothermal conversion efficiency in photocatalytic reactions; however, the intrinsic factors governing excitonic effects remain elusive. Herein, a series of single-atom catalysts with well-defined M1-N3C1(M = Mn, Fe, Co, and Ni) active sites are designed and synthesized to investigate the structure–activity relationship between photocatalytic materials and excitonic effects. Comprehensive characterization and theoretical calculations unveil that excitonic effects are positively correlated with the number of valence electrons in single metal atoms. The single Mn atom with 5.93 valence electrons exhibits the weakest excitonic effects, which dominate superoxide radical (O2•–) generation through charge transfer and enhance photothermal conversion efficiency. Conversely, the single Ni atom with 9.27 valence electrons exhibits the strongest excitonic effects, dominating singlet oxygen (1O2) generation via energy transfer while suppressing photothermal conversion efficiency. Based on the valence electron number dependent excitonic effects, a reaction environment with hyperthermia and abundant cytotoxic O2•–is designed, achieving efficient and stable water disinfection. This work reveals single metal atom dependent excitonic effects and presents an atomic-level methodology for catalytic application targeted reaction environment tailoring.

The development of low cost, metal free semiconductor photocatalysts for CO2reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2emissions. In this work, black phosphorus quantum dots (BPQDs) were successfully dispersed on a graphitic carbon nitride (g-C3N4) support viaa simple electrostatic attraction approach, and the activities of BP@g-C3N4composites were evaluated for photocatalytic CO2reduction. The BP@g-C3N4composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2reduction to CO (6.54 μmol g−1h−1at the optimum BPQDs loading of 1 wt%) compared with pure g-C3N4(2.65 μmol g−1h−1). This work thus identifies a novel approach towards metal free photocatalysts for CO2photoreduction. 开发还原二氧化碳生成燃料和有价值化学品的低成本、非金属半导体光催化剂, 是减少二氧化碳浓度的一种有效方案. 本工作通 过简单的静电吸引方法成功地将黑磷量子点(BPQDs)分散在石墨相氮化碳(g-C3N4)载体上, 成功制备了BP@g-C3N4复合材料, 并对其在紫 外-可见光激发下光催化还原CO2的性能进行了研究. 电化学表征, 瞬态吸收光谱和荧光光谱数据表明BPQDs的负载提高了g-C3N4的载流 子分离效率. 在氙灯的照射下, 与g-C3N4(CO的生成速率为2.1 μmol g−1h−1)相比, BP@g-C3N4复合材料光催化还原CO2活性显著提高(当 BPQDs的负载量为1 wt%时, CO的生成速率为6.54 μmol g−1h−1). 本工作发展了一种新型的可还原CO2的非金属基光催化剂.

Phosphorus-doped graphitic carbon nitrides (P-g-C3N4) have recently emerged as promising visible-light photocatalysts for both hydrogen generation and clean environment applications because of fast charge carrier transfer and increased light absorption. However, their photocatalytic performances on CO2reduction have gained little attention. In this work, phosphorus-doped g-C3N4nanotubes are synthesized through the one-step thermal reaction of melamine and sodium hypophosphite monohydrate (NaH2PO2·H2O). The phosphine gas generated from the thermal decomposition of NaH2PO2·H2O induces the formation of P-g-C3N4nanotubes from g-C3N4nanosheets, leads to an enlarged BET surface area and a unique mesoporous structure, and creates an amino-rich surface. The interstitial doping phosphorus also down shifts the conduction and valence band positions and narrows the band gap of g-C3N4. The photocatalytic activities are dramatically enhanced in the reduction both of CO2to produce CO and CH4and of water to produce H2because of the efficient suppression of the recombination of electrons and holes. The CO2adsorption capacity is improved to 3.14 times, and the production of CO and CH4from CO2increases to 3.10 and 13.92 times that on g-C3N4, respectively. The total evolution ratio of CO/CH4dramatically decreases to 1.30 from 6.02 for g-C3N4, indicating a higher selectivity of CH4product on P-g-C3N4, which is likely ascribed to the unique nanotubes structure and amino-rich surface.

Semimetal Bi decorated Bi4O5I2nanosheets showed excellent photo-thermocatalytic activity for CO2reduction under UV–vis-IR light.

In photocatalysis systems, precious metal co-catalysts play very important roles. Here, a photodeposition method is used to load Pt on different photocatalysts for photocatalytic CO2conversion testing. The performance results indicate that the selectivity of semiconductor photocatalysts for CO2reduction was effectively reversed from CO to CH4due to the introduction of Pt.

Metal-free graphitic carbon nitride (g-C3N4) has triggered huge interests for converting solar energy into fuels. However, direct-calcination derived bulk g-C3N4always suffers from low surface area and high recombination of charge carriers, prompting attempts to foster g-C3N4nano/microstructures to achieve high performance. Conventional routes, like templating method, always yields g-C3N4with tedious morphology and requires post-treatment. Here we release the first report on development of horn-like hollow mesoporous ultrathin (HHMU) g-C3N4tubes via first forming a horn-like Br-containing intermediate followed by further decomposition transformation under co-pyrolysis of melamine and substantial NH4Br. The multiple-superiorities achieved here (hollow/mesoporous/ultrathin/horn-like) allows g-C3N4high surface area, drastically boosted bulk charge separation, carrier density and surface charge transfer efficiency. This advanced g-C3N4thus casts outstanding photocatalytic performance for H2evolution with an apparent quantum efficiency (AQE) of 14.3% at 420 ± 15nm, far exceeding most of reported g-C3N4. HHMU g-C3N4also delivers a strengthened photocatalytic CO2reduction activity into CO and CH4. Selective photo-deposition results provide an in-depth insight into charge movement behavior and high photo-reactivity that the photo-generated electrons migrate to the outer shell and holes prefer to transfer onto the inner shell of HHMU g-C3N4tubes, thus achieving efficient spatial anisotropic charge separation. The current study may furnish a reference towards developing efficient tactics for integrally advancing g-C3N4for renewable energy generation, and disclose a new perspective into promoting charge separation via microstructure design.

Exciton and carrier photocatalytic processes have been proved in bismuth oxyhalogen photocatalysts. But, there are no reports about how to regulate the different mechanisms to improve photocatalytic activity for different reaction. Here, we found that the photocatalytic mechanisms could be regulated by changing the assembly method of bismuth, oxygen, and halogen atoms. Reactive oxygen species (ROS) experimentals results concluded that solid solution BiOBr0.5I0.5showed enhanced exciton photocatalytic process, and coupling 0.5BiOBr/0.5BiOI displayed improved carrier photocatalytic proces. This work promoted the understanding about solid solution and coupling for bismuth oxyhalogen.

{001} facet dominated BiOBr nanosheets are fabricated viaa facile hydrothermal method in the presence of nitric acid without any organic additive and applied for CO2photoreduction. The concentration of nitric acid easily regulates the thickness of the obtained BiOBr nanosheets. When employing concentrations of 0, 0.1, 0.5, 1 and 4 M nitric acid, the corresponding surface area and percentage of exposed {001} facets of BiOBr-0, BiOBr-0.1, BiOBr-0.5, BiOBr-1 and BiOBr-4 nanosheets significantly increase in sequence. BiOBr-0 nanosheets are incapable of converting CO2into CO. However, BiOBr-0.1, BiOBr-0.5, BiOBr-1 and BiOBr-4 nanosheets show successively enhanced CO2photoreduction performance. Surprisingly, they exhibit high selectivity for converting CO2into CO with negligible generation of CH4. In particular, BiOBr-4 shows the highest CO production rate of 4.45 μmol g−1h−1under simulated sunlight irradiation. The electronic structure analysis demonstrates that the conduction band minimum is significantly raised to endow BiOBr-4 with reduction power for CO2/CO conversion, in comparison with the incapability of BiOBr-0. The breakthrough in CO2reduction of BiOBr-4 nanosheets is ascribed to the larger active surface area, higher electron transfer, more effective charge carrier separation and significantly raised reduction ability.

Bismuth-rich bismuth oxyhalides (Bi–O–X; X = Cl, Br, I) display high photocatalytic reduction activity due to the promoting conduction band potential. In this work, two Bi5O7I nanosheets with different dominant facets were synthesized using either molecular precursor hydrolysis or calcination. Crystal structure characterizations, included X-ray diffraction patterns (XRD), field emission electron microscopy and fast Fourier transformation (FFT) images, showed that hydrolysis and calcination resulted in the dominant exposure of {100} and {001} facets, respectively. Photocatalytic data revealed that Bi5O7I–001 had a higher activity than Bi5O7I–100 for N2fixation and dye degradation. Photoelectrochemical data revealed that Bi5O7I–001 had higher photoinduced carrier separation efficiency than Bi5O7I–100. The band structure analysis also used to explain the underlying photocatalytic mechanism based on the different conduction band position. This work presents the first report about the facet-dependent photocatalytic performance of bismuth-rich Bi–O–X photocatalysts.

It is the first report for synthesizing Bi4O5I2and Bi5O7I ultrathin nanosheets with non-hydrothermal methods. Furthermore, it was found the selective photoreduction of CO2into CO.