Conduction Band Of g-C3N4 Research Articles

Conductive Co1.5MoS3.2 promoted photocatalytic H2 production over g-C3N4.

In this work, Co1.5MoS3.2 (CMS) nanoparticles were synthesized using a one-step hydrothermal approach, series CMS/g-C3N4 photocatalysts with various CMS amount were obtained using a physical solvent evaporation method. The investigation indicates that introducing CMS as cocatalysts can greatly enhance the H2 production activity of g-C3N4 by two orders of magnitude. The H2 production rate reaches up to 17607 μmol·g−1·h−1 over 40 wt% CMS/g-C3N4, resulting in a 185-fold increase when compared to the unmodified g-C3N4 (94.8 μmol·g−1·h−1), far better than 40 wt% MoS2/g-C3N4 (125.2 μmol·g−1·h−1), 40 wt% Co3S4/g-C3N4 (7948.6 μmol·g−1·h−1), even widely 3 wt% Pt/g-C3N4 (12803 μmol·g−1·h−1). The improvement can be ascribed to the Schottky junction effect between CMS and g-C3N4, the highly conductive CMS can receive electrons from the conduction band of g-C3N4, preventing charge recombination. Meanwhile, CMS can obviously lower the H2 evolution potential and provide more active site for the H2 evolution reaction, those all lead to a faster H2 evolution kinetics. Additionally, CMS as a cocatalyst offers advantages such as simple preparation, low cost, and remarkable effectiveness, making it highly promising for further development.

Boosting excitons dissociation in defective-rich graphitic carbon nitride for efficient hydrogen peroxide photosynthesis and on-site environmental governance

Solar-driven hydrogen peroxide (H2O2) production offers a sustainable strategy to address the ever-growing demand of eco-friendly oxidant and clean fuel, while its efficiency highly relies on the generation of desired reactive oxygen species (ROSs). Herein, we demonstrate that introducing boron-nitrogen vacancy (B-NV) associates in g-C3N4 enables to weaken the robust excitonic effect and promote bound excitons spontaneously dissociating into free charge carriers under ambient conditions. Specifically, the doped B atoms introduced a donor state below the conduction band of g-C3N4, which disturbs charge distribution around heptazine rings and further destabilizes excitons. The concomitant NV, serving as an accepter state locating above the valence band, cooperates with the doped B atoms to form B-NV associates that simultaneously downshifts the conduction band and valence band of g-C3N4. Distinct from the counterpart preferring to activate O2 into 1O2 via an energy-transfer-involved pathway, g-C3N4 featuring with B-NV associates displayed a superior photoactivity of visible-light-driven two-electron oxygen reduction reaction for H2O2 production with a yield of 182 μmol h−1 and selectivity of 100%. The produced H2O2 could effectively degrade organic contaminants and kill typical bacteria. This study highlights the importance of ROSs generation in two-dimensional photocatalysts for sustainable solar-to-chemical conversion and on site environmential governance.

Enhanced photocatalytic hydrogen production of S-scheme TiO2/g-C3N4 heterojunction loaded with single-atom Ni

S-scheme heterostructure photocatalysts can achieve highly efficient solar energy utilization. Here, single-atom Ni species were deposited onto TiO2/g-C3N4 (TCN) composite photocatalyst with an S-scheme heterojunction for highly efficient photocatalytic water splitting to produce hydrogen. Under solar irradiation, it realized the hydrogen production activity of 134 µmol g–1 h–1, about 5 times higher than the TCN without atomic Ni. In-situ Kelvin probe force microscopy characterization and the density functional calculation certify that by forming the S-scheme heterojunction, the photo-excited electrons from the TiO2 combine with the photogenerated holes at the coupled g-C3N4 driven by a built-in electric field. More importantly, the single-atom Ni species stabilized the photogenerated electrons from the g-C3N4 could effectively enhance the charge separation between the holes on the valence band of TiO2 and electrons at the conduction band of g-C3N4. Meanwhile, the Ni atoms act as the surface catalytic centers for the water reduction reaction, which greatly improves the reactivity of the photocatalyst. The present work provides a new approach for developing noble metal-free heterojunctions for high-efficiency photocatalysis.

Ti3C2 MXene-induced interface charge transferred in Z-scheme heterojunction for efficient photocatalytic removal of nitric oxide

Currently, NO pollution is an urgent challenge for us to face, and photocatalytic degradation has been recognized as one of the most promising methods to reduce it. As a representative photocatalyst, g-C3N4 has attracted researchers because of its low cost and excellent performance. In this work, a new triphasic Z-scheme heterostructure was built, TiO2/Ti3C2 MXene/g-C3N4, to improve the visible-light irradiation-induced NO removal efficiency of g-C3N4. In this Z-scheme heterostructure, Ti3C2 MXene could form a directional electron transfer thoroughfare between g-C3N4 and TiO2 to accelerate the electronic transmission rate, meanwhile, due to the specificity of the band structure, electrons on conduction band of g-C3N4 and holes on valence band of TiO2 can be well separated and react with the adsorbed species to achieve good photocatalytic performance. Because of the triphasic heterostructure formed by TiO2, Ti3C2 MXene and g-C3N4, the efficiency of this compound for visible-light irradiation-induced NO removal improves from 32% to 56%. This work provides a new strategy to improve NO removal efficiency and shows a broader application prospect of photocatalysts with a triphasic structure.

Interfacial charge separation of nickel tungstate anchored on g-C3N4 heterojunction stimulates visible-light driven direct Z-scheme photoelectrochemical hydrogen evolution

Active photocathodes are required for the photo(electro)chemical hydrogen evolution reaction (PEC-HER) in a highly efficient solar-to-hydrogen fuel conversion process aided by solar assisted water splitting. Here, we used a simple one-pot solvothermal method to prepare NiWO4/g-C3N4 nanocomposites for PEC-HER using low-cost, metal-free photocatalysts such as graphitic carbon nitride (g-C3N4) and nickel tungstate (NiWO4). Subsequently, the physicochemical and optoelectronic nature of the as-synthesized materials were studied by spectroscopic methods. As part of a direct Z-scheme heterogeneous mechanism, the photoactive module, g-C3N4 was blended with NiWO4 in varying ratios to enhance the efficiency of charge separation in PEC-HER. As expected, the established NiWO4/g-C3N4 nanocomposite demonstrates an enhanced photo(electro)catalytic activities compared to the single components. It is firmly due to the presence of intimate interfacial interaction between g-C3N4 and NiWO4, which further supports the existence of electrons in the conduction band of g-C3N4 and holes in the valence band of NiWO4. The prepared NiWO4/g-C3N4 nanocomposite with 15 wt% of g-C3N4 showed an enhanced photocurrent density of 167.81 mA cm−2, which is higher than that of other prepared photo(electro)catalysts and confirms its excellent charge separation efficiency as well as very low electron-hole recombination rate. Besides, the photoelectrochemical activities of the prepared materials were analysed through a PEC-HER, revealing that the developed NiWO4/g-C3N4 nanocomposite as photocathode requires a low overpotential of 0.048 V to reach the current density of 10 mA cm−2 and a Tafel slope of 43 mV dec−1, indicating the superiority of the photo(electro)catalyst. In addition, the NiWO4/g-C3N4 photocathode exhibits excellent performance for PEC-HER with higher stability.

Influence of the calcination duration of g-C3N4/TiO2 “veggie-toast-like” photocatalyst on the visible-light triggered photocatalytic oxidation of bisphenol A

Two commercially available TiO2 (hexagonal-like and spherical-like particles) were used to investigate the effect of g-C3N4 “melting” on the photocatalytic properties of g-C3N4/TiO2 composites. Improvement in the contact between the components was observed when they were thermally treated at 350 °C for an extended period of time (between 2 and 72 h) due to the partial melting and phase fusion of g-C3N4. Consequently, the enhanced contact between the phases allows easier injection of photogenerated electrons from the conduction band of g-C3N4 into TiO2, improving charge carrier separation. The prepared composites were tested for bisphenol A degradation under visible-light illumination, which showed that the components that had been calcined for 24 h performed better due to the improved charge carrier separation. Superoxide anionic radicals and photogenerated holes were identified as active species in the photooxidation experiments conducted under visible-light illumination.

Constructing C–O bridged CeO2/g-C3N4 S-scheme heterojunction for methyl orange photodegradation：Experimental and theoretical calculation

Owing to its feasibility, efficiency in light-harvesting and effectiveness in the interfacial charge transfer between two n-type semiconductors, constructing heterojunction photocatalysts have been identified as an effective way for enhancing the photocatalytic properties. In this research, a C–O bridged CeO2/g-C3N4 (cCN) Step-scheme (S-scheme) heterojunction photocatalyst was constructed successfully. Under visible light irradiation, the cCN heterojunction exhibited the photocatalytic degradation efficiency of methyl orange, which was about 4.5 and 1.5 times higher than that of pristine CeO2 and CN, respectively. The DFT calculations, XPS and FTIR analyses demonstrated the formation of C–O linkages. And the calculations of work functions revealed the electrons would flow from g-C3N4 to CeO2 due to the difference in Fermi levels, resulting in the production of internal electric fields. Benefiting from the C–O bond and internal electric field, the photo-induced holes in the valence band of g-C3N4 and the photo-induced electrons from conduction band of CeO2 would be recombined when exposed to visible light irradiation, while leaving the electrons with higher redox potential in the conduction band of g-C3N4. This collaboration accelerated the separation and transfer rate of photo-generated electron-hole pairs, which promoted the generation of superoxide radical (•O2−) and improved the photocatalytic activity.

Synergism between chemisorption and unique electron transfer pathway in S-scheme AgI/g-C3N4 heterojunction for improving the photocatalytic H2 evolution

AgI/g-C3N4 S-scheme heterojunction with a unique electron transfer pathway was developed as a catalyst for H2 evolution. We discussed the behavior of chemisorption and photoexcited charge carriers in photocatalytic reduction on the S-scheme AgI/g-C3N4 heterojunction. It was demonstrated that the path of charge transfer mediated by S-scheme AgI/g-C3N4 heterojunction was favorable for the improvement of electron utilization in photocatalysis. The advantage of S-scheme heterojunction was that the holes in the valence band (VB) of g-C3N4 could recombine with the electrons in the conduction band (CB) of AgI due to the built-in electric field. Electrons on the CB of g-C3N4 and holes on the VB of AgI were preserved for further photocatalytic reaction. Therefore, a distinctive electron transfer pathway was introduced in the S-scheme heterojunction. In addition, the lifetime of charge carriers was prolonged, and the reduced ability of electrons was increased as compared to reference g-C3N4. It not only decreased the energy required for electron excitation, but also reduced the energy consumption for the charge transfer. This paper provided a new strategy to improve the utilization of photogenerated electrons and chemisorption of water for photocatalytic H2O splitting.

Synergism between nitrogen vacancies and a unique electrons transfer pathway of Ag modified S-scheme g-C3N4/CdS heterojunction for efficient H2 evolution

Ag modified g-C3N4/CdS (Ag@g-C3N4/CdS) S-scheme heterojunction with a distinctive charge transfer channel was prepared as a photocatalyst for photoreduction of H2O. The effect of nitrogen vacancies and photo-excited charge carriers in the water splitting on the Ag@g-C3N4/CdS was discussed. It was found that the charge carriers transport channel in Ag@g-C3N4/CdS S-scheme heterojunction was instrumental in the enhancement of H2 production. The electrons in Ag nanospheres and in the conduction band (CB) of CdS can recombine with the holes in the valence band (VB) of g-C3N4, which prolonged the lifetime of electrons in the CB of g-C3N4. Meanwhile, a unique charge transfer channel was produced in the Ag@g-C3N4/CdS. Compared with g-C3N4, Ag@g-C3N4/CdS photocatalyst demonstrated an enhanced performance which was assigned to the increased charge carrier lifetime. The supreme Ag@g-C3N4/CdS showed photocatalytic H2 production activity up to 204.19 μmol for 4 h under illuminate (λ ≥ 420 nm), which was 11.74 times than that of g-C3N4.

Supramolecule self-assembly approach to direct Z-scheme TiO2/g-C3N4 heterojunctions for efficient photocatalytic degradation of emerging phenolic pollutants

To improve the visible-light photocatalytic oxidation activity of anatase TiO2 or graphitic carbon nitride (g-C3N4) towards organic pollutants, the present work develops a supramolecule self-assembly approach combined with thermal polycondensation to construct direct Z-scheme-dictated TiO2/g-C3N4 heterojunctions. This in-situ route not only leads to the TiO2/g-C3N4 with porous sheet-like nanostructures but also establishes hydrogen-bonded intimate interfacial contact between TiO2 and g-C3N4. The TiO2/g-C3N4 heterojunctions demonstrate significantly enhanced visible-light photocatalytic activity in the degradation of emerging phenolic pollutants, acetaminophen and methylparaben, as compared with TiO2, P25 TiO2 and g-C3N4; additionally, TiO2-to-g-C3N4 molar ratio in the heterojunctions influences the activity remarkably. This enhanced photocatalytic oxidation performance is mainly ascribed to the direct Z-scheme-dictated charge carrier transfer mechanism, driven by well-matched energy band structures of TiO2 and g-C3N4 as well as the intimate interfacial contact between TiO2 and g-C3N4. Accordingly, the spatial separation of the photogenerated charge carriers is boosted; simultaneously, strong redox ability of electrons on conduction band of g-C3N4 and holes on valence band of TiO2 is retained. Therefore, abundant reactive oxygen species like •O2− anion radicals and •OH radicals are generated. These reactive oxygen species together with holes are responsible for the elevated photocatalytic oxidation performance of TiO2/g-C3N4 heterojunctions.

Hollow spherical biomass derived-carbon dotted with SnS2/g-C3N4 Z-scheme heterojunction for efficient CO2 photoreduction into CO

The core of realizing the effective CO2 conversion by solar energy is to develop a stable photocatalyst with high CO2 adsorption capacity and high charge separation efficiency. In this work, a hollow spherical Z-scheme SnS2/g-C3N4/C (SCC) photocatalyst is successfully constructed by a morphology-inherited strategy. Biomass mabospores are utilized as both the precursor for formation of hollow spherical structure and carbon source, and the g-C3N4 and SnS2 nanosheets tightly anchor on the surface of mabospores-derived carbon spheres. The Z-scheme SCC heterostructure exhibits 5.5 times activity enhancement on CO2 photoreduction to CO with a high evolution rate up to 40.86 μmol∙g−1∙h−1. Examined by various photoelectrochemical analysis, the boosted photocatalytic activity originates mainly from the construction of hollow spherical Z-scheme heterojunction, providing the more preferable basic sites for CO2 adsorption, promoting the separation efficiency of electron-hole pairs, as well as increasing the reductionability of electrons in conduction band of g-C3N4. The formed internal electric fields between the g-C3N4 and SnS2 can also further reinforce the spatial separation of photogenerated charge carriers. Theoretical calculations further verify that the SCC Z-scheme heterostructure can effectively decrease the energy barriers of formed intermediates, especially the crucial COOH*, and thus leading to the facile conversion of CO2-to-CO. This work induces a new strategy to construct g-C3N4-based Z-scheme heterojunction assisted by versatile biomasses with optimized structure and enhanced photoelectrochemical merits for efficient CO2 conversion into chemical fuels.

Constructing a novel NaLa(WO4)2/g-C3N4 Z-scheme heterojunction with efficient carrier separation for excellent photocatalytic purification of NO

In this paper, a novel NaLa(WO4)2/g-C3N4 photocatalyst with Z-scheme heterojunction was synthesized for the first time, and the photocatalytic purification of NOx was used as an evaluation method of its activity. The structure was analyzed in depth by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and other characterization methods. NaLa(WO4)2 and g-C3N4 have obvious interfaces and successfully constructed a Z-scheme heterojunction structure. The combination of photogenerated electrons on the conduction band (CB) of NaLa(WO4)2 with holes on the valence band (VB) of g-C3N4 leads to the accumulation of the remaining holes and electrons on the VB of NaLa(WO4)2 and CB of g-C3N4, and finally realizes the effective separation of photogenerated carriers and maintains the high redox ability of the catalyst. The NaLa(WO4)2/g-C3N4 composite catalyst has a highest NO purification rate of 47.18%, which is 16.51% higher than pure g-C3N4. Moreover, the In-situ DRIFTS monitors the reaction intermediates and final products of NO on the NaLa(WO4)2/g-C3N4 heterojunction surface under visible light irradiation, and provides the corresponding reaction equations. This work provides a new type of photocatalyst that is easy to prepare and highly active, as well as a low-cost photocatalytic treatment technology to remove NO in the environment.

Interface engineering of Z-scheme α-Fe2O3/g-C3N4 photoanode: Simultaneous enhancement of charge separation and hole transportation for photoelectrocatalytic organic pollutant degradation

A series of g-C3N4-modified α-Fe2O3 heterostructures are synthesized by deposition on fluorine-doped tin oxide (FTO). The resulting α-Fe2O3/g-C3N4/FTO photoanode (denoted as Fe/CN) show markedly improve photoelectrocatalytic performance, with a photocurrent density (0.18 mA/cm2) that is 5.1 times that of α-Fe2O3 and 9.4 times that of g-C3N4. The suitable charge transport path is observed by interfacial analysis, where the conduction band of g-C3N4 and valence band of α-Fe2O3 shuttled holes and electrons into the electrolyte at accelerated speeds, respectively. Impressively, the Fe/CN photoelectrode achieve the highest pollutant removal efficiency of 99.7% for the photoelectrocatalytic degradation of clofibric acid (CA) under visible-light irradiation, which is expected to be applicable in actual wastewater for environmental protection. Density functional theory (DFT) calculations and intermediate identification shows that the CA degradation pathway involved C–Cl and O–C cleavage. These findings provide an environmentally friendly method to remove emerging contaminants using renewable solar energy.

Ammonia-nitrogen removal from water with gC3N4-rGO-TiO2 Z-scheme system via photocatalytic nitrification-denitrification process

Photocatalytic removal of NH3–N is expected to be an alternative to the biological method that accompanied with high energy consumption and secondary pollution. However, NH3–N is always oxidized into nitrate and nitrite during the photocatalytic processes, which also need to be removed from the water. Herein, the g-C3N4/rGO/TiO2 Z-scheme photocatalytic system was prepared and used for the NH3–N removal. The results showed the rate constant of NH3–N conversion on it was 0.705 h−1, 1.7 times as high as that on g-C3N4/TiO2, and most of the NH3–N were converted into gaseous products. And the experiment result indicated NH3–N and NO3− in water could enhance the removal of each other. According to the results, the main reaction mechanism is speculated as: ·OH radicals and ·O2− radicals were generated on TiO2 and oxidized the NH3–N into NO3−, and the latter was reduced into non-toxic N2 on the conduction band of g-C3N4. Finally, NH3–N removal performance for actual coking wastewater was investigated, and the stability of the photocatalyst was tested. This work provides some theoretical basis for the two-step degradation of pollutants by Z-scheme photocatalytic system.

Fabrication of CuS-modified inverse opal g-C3N4 photocatalyst with enhanced performance of photocatalytic reduction of CO2

As a greenhouse gas, CO2 is also a rich carbon resource. Using sunlight to reduce CO2 to usable substances through photocatalysis can alleviate the greenhouse effect and realize energy recycling. Herein, CuS nanoparticles are grown in situ on the surface of inverse opal g-C3N4 by a one-step hydrothermal method. The inverse opal structure can increase the specific surface area of the material, and CuS can be used as the cocatalyst to accept photo-generated electrons on the conduction band of g-C3N4, thereby promoting the separation and transfer of photo-generated charges. And the interfacial charge transfer mechanism of CuS further improves the separation efficiency of photogenerated electrons and holes. The photocatalytic reduction of CO2 activity of the prepared catalyst is greatly improved. The CO yield reaches 13.24 μmol g−1 h−1. A new strategy is provided to develop artificial photosynthesis for reduction of CO2.

Stable LSPR effect and full-spectrum photocatalytic water purification by g-C3N4−x/MoO3−x with passivated interface oxygen vacancies

Interface passivation to construct a Z-scheme heterojunction can not only improve the separation efficiency and redox ability of photo-generated carriers, but also retain the excellent optical properties of non-metallic plasma. In this work, the optical performance and carrier dynamics of g-C3N4−x/MoO2.69(OH)0.31 heterojunction were optimized by passivating the interface oxygen vacancies. The adsorption of -OH groups on the surface oxygen vacancy sites of MoO2.69(OH)0.31 was hindered due to the formation of heterogeneous interface. This in turn significantly inhibited the charge recombination at the oxygen vacancy-induced deep trap states, while maintaining the stable and continuously enhanced visible-near infrared light absorption. The conduction band of g-C3N4−x provided the appropriate energy platform to accept the photo-generated electrons of MoO2.69(OH)0.31, resulting in the high utilization of high-energy “hot electrons”. The prepared g-C3N4−x/MoO2.69(OH)0.31 heterojunction showed the enhanced full-solar-spectrum photocatalytic performance for the degradation of the organic pollutants. Moreover, Ti3C2 nanosheet-wrapped g-C3N4−x/MoO3−x was synthesized to alleviate the photo-corrosion of g-C3N4−x/MoO3−x. The composite photocatalyst exhibited the further improved photocatalytic activity while maintaining good recyclability and structural stability. This work provided a new strategy for the preparation of defect-mediated heterojunction photocatalysts with high activity and stability.

α-MnO2 modified exfoliated porous g-C3N4 nanosheet (2D) for enhanced photocatalytic oxidation efficiency of aromatic alcohols

Porous graphitic carbon nitride (g-C3N4) was synthesized by taking melamine and ammonium bicarbonate through single-step calcination method followed by ultrasonication to obtain exfoliated porous g-C3N4 (2D) nanosheets. Further enhancement of photocatalytic performance, g-C3N4 nanosheet (2D) was further modified with different weight percentage of (1, 3, 5, and 7) of MnO2. The introduction of α-MnO2 onto the g-C3N4 nanosheet establishes an interlayer channels to promote the migration of charge carriers through the valence band and conduction band of the prepared composite MnO2@g-C3N4. The transformation of photo induced charge carriers adopt the Z-scheme mechanism rather band-transfer mechanism. The accumulated photo generated electrons in conduction band of g-C3N4 is more electro negative than the potential of (O2/O2–.) and able to reduce oxygen to superoxide (O2–.) radical. At the same time, the holes in valence band of α-MnO2 are more electro positive than the potential of (OH–/OH.) and help in oxidate OH– to hydroxyl (OH.) radical. Among all the composites, 3 wt% MnO2 modified g-C3N4 shows the best photocatalytic oxidation efficiency towards all the aromatic alcohols. In presence of visible light, heterojuction formation, and formation of active charged species (OH. and O2–.) were mostly responsible for photocatalytic oxidation of aromatic alcohols through free radical mechanism.

Photoelectrochemical aptasensing for thrombin based on exonuclease III-assisted recycling signal amplification and nanoceria enzymatic strategy

In the present work, a capture DNA (c-DNA) was immobilized on the TNA/g-C3N4 to develop a sensitive and selective TNA/g-C3N4/c-DNA photoelectrochemical aptasensor for determining thrombin. With the aid of the specific recognition of anti-thrombin aptamer towards thrombin, ingenious design of hairpin DNA, and exonuclease III-assisted recycling signal amplification, more nanoceria could be assembled on the TNA/g-C3N4/c-DNA to form TNA/g-C3N4/nanoceria in the presence of thrombin. Due to the oxidase-mimic catalytic efficiency of nanoceria and the oxygen consumption for glucose oxidation, the photoexcited electrons at the conduction band of g-C3N4 could be well transferred to that of TNA under visible light irradiation, resulting in the increase of the photocurrent of TNA/g-C3N4/nanoceria, and the increase value of photocurrent had a linear relationship with the concentration of thrombin under the optimal conditions. So, the constructed TNA/g-C3N4/c-DNA photoelectrochemical aptasensor exhibited a satisfactory quantitative range from 0.01 pM to 0.5 nM, low detection limit with 3.4 fM for thrombin determination, and was applied for the human serum analysis successfully with RSD of less than 4.8% and the recovery between 95% and 113%.

Facile construction of 2D g-C3N4 supported nanoflower-like NaBiO3 with direct Z-scheme heterojunctions and insight into its photocatalytic degradation of tetracycline

Photocatalytic oxidation using solar energy is a promising green technology to degrade antibiotic contaminants. Herein, a 2D g-C3N4 supported nanoflower-like NaBiO3 with direct Z-scheme heterojunction was synthesized via a facile hydrothermal approach, and the photocatalytic performance of g-C3N4/NaBiO3 was remarkable better than that of g-C3N4 and NaBiO3 for tetracycline degradation under visible light. Photoinduced electrons accumulated on the conduction band of g-C3N4 and holes gathered on the valence band of NaBiO3, which was more suitable for generating superoxide and hydroxyl radicals. Meanwhile, the built-in electric field between g-C3N4 and NaBiO3 was proved by their different work functions based on DFT calculations, which enhanced the charges separation. The formed radicals were determined by ESR, and their role in the degradation of tetracycline was examined by the active species trapping test. Moreover, the sites attacked by free radicals and degradation pathways for tetracycline were inferred by the results of Gaussian 09 program and HPLC-MS. The effects of water matrix and three other organic contaminants was further studied for actual use evaluation. Importantly, the prepared g-C3N4/NaBiO3 showed stable photodegradation activity for eight cycles. This work not only provides a promising photocatalyst, but also gets insight into the photocatalytic removal of tetracycline.

Efficient production of acetate from inorganic carbon (HCO3–) in microbial electrosynthesis systems incorporating Ag3PO4/g-C3N4 anaerobic photo-assisted biocathodes

The efficient production of acetate from HCO3− by the nonphotosynthetic bacterium Serratia marcescens Q1 is demonstrated in an anaerobic, photo-assisted, microbial electrosynthesis (MES) system incorporating a Ag3PO4/g-C3N4 biocathode. The Ag3PO4/g-C3N4 formed a Z-scheme photocatalytic heterojunction structure with enhanced redox capacity. The photocorrosion of Ag3PO4 was inhibited by the production of H2O2 in-situ, through water oxidation driven by the photogenerated holes on the Ag3PO4 valence band. The photoinduced electrons on the conduction band of g-C3N4 instead produced H2, which was metabolized by the Q1 electrotroph with HCO3− to produce acetate at a rate of 5.4 mM/d with a CEacetate of 93 % at a current density of 3.3 A/m2. The MES accumulated up to 81.0 mM with a CEacetate of 89 % over 16 days continuous operation. This study provides a sustainable and feasible strategy for inhibiting the photocorrosion of Ag3PO4 and thus achieve efficient acetate production from HCO3− in photo-assisted MESs biocathodes.