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The use of metal single atoms (SAs) as co‐catalysts on semiconductors has emerged as a promising technology to enhance their photocatalytic hydrogen production performance. In this study, we describe the deposition of very low amounts of Pt SAs (<0.1 at %) on exfoliated graphitic carbon nitride (C3N4) by a direct Pt−deposition approach from highly dilute chloroplatinic acid precursors. We find that − using this technique−a remarkably low loading of highly dispersed Pt SAs (0.03 wt %) on C3N4 is sufficient to achieve a drastic decrease in the overall charge transfer resistance and a maximized photocatalytic efficiency. The resulting low‐loaded Pt SAs/C3N4 provides a H2 production rate of 1.66 m mol/h/mg Pt, with a remarkable stability against agglomeration; even during prolonged photocatalytic reactions no sign of light‐induced Pt agglomerations can be observed. We ascribe the high performance and stability to the site‐selective, stable coordination of Pt within the C3N4 structure. Notably the H2 production rate of the low‐loaded Pt SAs surpasses the activity of Pt SAs deposited by other techniques or nanoparticles at comparable or even higher loading – the optimized Pt SAs decorated C3N4 show ≈5.9 times higher rate than Pt NP decorated C3N4. [ABSTRACT FROM AUTHOR]

Atom-thin SnO 2 (a-SnO 2) shows promising potential for applications in gas sensors. However, its high working temperature can cause agglomeration, leading to a decrease in the specific surface area and resulting in performance deterioration of the sensors. In this study, g-C 3 N 4 was utilized as a thermal support to address this issue and improve the gas-sensing properties of a-SnO 2. When a-SnO 2 was grown with 10 wt% g-C 3 N 4 dispersed evenly in ethylenediamine, the gas-sensing performance of the composite improved significantly, including the response value (R a / R g = 8.8–10 ppm HCHO), fast response (τ res = 1.6 s), ultralow detection limit (0.1 ppm), long-term stability and humidity-resistance properties. This work not only introduces a method to utilize a thermal support for atom-thin metal oxides, enhancing their stability at high working temperatures but also investigates the underlying mechanism. This study provides valuable insights into the application of ultrathin metal oxides. Additionally, it facilitates the development of a portable smart system for detecting HCHO contamination in practical settings. [ABSTRACT FROM AUTHOR]

The photocatalytic conversion of ethanol and the simultaneous development of hydrogen technology play a role in solving the energy crisis and reducing environmental pollution. In this research, rod-like M-MoS2 serves as a channel for charge transfer, leading to superior photocatalytic activity compared to H-MoS2. Further, two-dimensional (2D) B-doped C3N4 (BCN) nanosheets were anchored on the one-dimensional (1D) rod-like M-MoS2 surface to form a 1D/2D heterojunction, with M-MoS2/BCN-0.08 (mass ratio of M-MoS2:BCN of 0.08:1) exhibiting the highest photocatalytic performance. Under visible light irradiation, the ethanol conversion rate reached 1.79% after 5 h of photocatalytic reaction per gram of catalyst, while generating 421 μmol of 2,3-butanediol (2,3-BDO), 5460 μmol of acetaldehyde (AA), and 5410 μmol of hydrogen gas (H2). This different characterization provides evidence that a significant amount of photoinduced electrons generated in BCN under illumination conditions rapidly transfer to the conduction band (CB) of M-MoS2 through the rod-like structure of M-MoS2, and finally transfer to Pt to promote the production of hydrogen gas. The photoinduced holes in the valence band (VB) of M-MoS2 are rapidly consumed by ethanol upon transferring to BCN, effectively separating the photoinduced electron–hole pairs and resulting in superior photocatalytic performance. [ABSTRACT FROM AUTHOR]

The C3N4/AlFeO3 photocatalysts were synthesized successfully via a sol-gel route and low temperature calcination process. When C3N4 is coupled with AlFeO3 to form a special heterojunction, the crystal structure, composition and optical band gap of the main lattice phase are not changed. However, its surface morphology, optical absorption coefficient and photocatalytic activity are greatly improved compared with pure C3N4 and AlFeO3. Photocatalytic experiments confirmed that the C3N4/AlFeO3 photocatalyst showed high photocatalytic activity for degradation of methyl orange under visible light irradiation, and its degradation rate was 9.40 times that of C3N4 and 5.13 times that of AlFeO3. The optimal catalyst content, dye concentration and pH value are 1 g/L, 20 mg/L and 5, respectively. Capture and stability experiments confirmed that the C3N4/AlFeO3 photocatalyst is recyclable, and holes, hydroxyl radicals and superoxide radicals are the main active species in the photocatalysis process. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide/carbon nitride (rGO/C3N4) nanocomposites were prepared through a low-temperature and low-pressure sintering method using a mixture of GO and C3N4 powders. The degradation performance of methylene blue (MB) of composites with different raw material ratios was studied under simulated solar irradiation conditions. Results indicated that GO was rapidly reduced during heat treatment and bonded well with C3N4. The C3N4 grains were also significantly refined. Compared with single-phase C3N4, the addition of GO greatly improved its photocatalytic efficiency and effectively suppressed the recombination of electron hole pairs. The samples exhibited good photocatalytic performance under simulated sunlight irradiation. Within 15 min, MB could be rapidly degraded by the C3N4/20% rGO composite. [ABSTRACT FROM AUTHOR]

In this study, nitrogen and sulfur co-doped carbon quantum dots (NSCQDs) were prepared by hydrothermal method, carbon nitride (C3N4) was fired in a muffle furnace in an air atmosphere, and finally, the ternary heterostructure of NSCQDs, C3N4 and bismuth oxide bromide (BiOBr) was synthesized by a hydrothermal method (NSCQDs/C3N4/BiOBr). The morphology of the catalyst was observed through SEM and TEM. The chemical bonds were analyzed by XPS and FT-IR to further confirm that NSCQDs and C3N4 were successfully attached to BiOBr. The photocatalytic activity of the synthesized catalysts was studied by degrading RhB under simulated light source. The experiment results showed that under optimal conditions, the degradation rate of RhB by NSCQDs/C3N4/BiOBr within 20 min was as high as 99.9%, which was much higher than that of pure BiOBr (33.5%). The degradation curve was combined with a pseudo-first-order kinetic model with a kinetic constant of 0.32578 min−1, which was 17.7 times that of BiOBr (0.01837 min−1). Catalyst recycling tests showed that NSCQDs/C3N4/BiOBr had extremely high stability. The active species quenching test showed that O 2 · - and 1O2 were the main active species during the photocatalytic process. The inhibition effect of NSCQDs and C3N4 on BiOBr photogenerated carrier recombination was analyzed by photoluminescence and transient photocurrent tests. This study is expected to provide an attractive strategy for constructing efficient and environmentally friendly photocatalysts for environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] The construction of CN/UiO-67 (CNU) S-scheme heterojunction composites through in situ formation of UiO-67 on carbon nitride (C 3 N 4) helps to address the limitations of carbon nitride (CN) in photocatalytic NO elimination. The optimized CNU 3 demonstrates superior photocatalytic efficiency, which is attributed to electronic channels constructed by Zr-N bonds and S-scheme electron transport mechanism, effectively promoting the efficient separation of photogenerated charge carriers with high redox potentials. Density Functional Theory (DFT) calculations reveal redistributed electronic orbitals in CNU 3 , with progressive and continuous energy levels near the Fermi level, which bolsters electronic conduction. Comprehensive quenching experiments, Electron Paramagnetic Resonance (EPR), and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analyses highlight a synergistic interplay of electrons, holes, and superoxide radicals in CNU 3 , inhibiting the generation of toxic nitrogen oxide intermediates and culminating in highly efficient photocatalytic NO oxidation. This study not only elucidates the mechanisms underpinning the enhanced performance of CNU 3 heterojunctions but also offers new perspectives on the preparation and interfacial charge separation of heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (C 3 N 4) emerges as an exceptionally promising photocatalyst thanks to its favourable characteristics, such as being non-metallic, sourced from abundant raw materials, and possessing outstanding thermal, physical, and chemical stability. Defects-induced C 3 N 4 plays a crucial role in enhancing photo-catalytic activity. In this study, the authors utilize the conventional sintering method to prepare g-C 3 N 4 by employing mixed precursors, namely melamine and thiourea. The band alignment between n - n type C 3 N 4 samples derived from these two different precursors was meticulously established. Four distinct compositions of C 3 N 4 are obtained by varying the weight ratios of melamine and thiourea during the in-situ synthesis. Various analytical methods thoroughly investigate these samples' physical/photo-chemical properties. Among the various samples, MT-GCN-A, characterized by a higher melamine (1.0 g) and lower thiourea (0.25 g) weight ratio, demonstrated superior attributes. These include a high specific surface area (14.28 m2 g−1), pore size (23.57 nm), and lower band gap (2.85 eV) in comparison to the other samples. When utilized as a photocatalyst for degrading Congo red (CR) under UV and visible-light irradiation, MT-GCN-A exhibited enhanced performance compared to the diverse samples. These findings highlight that the thoughtful combination of melamine and thiourea in C 3 N 4 facilitates efficient separation and transfer of photo-generated electron-hole pairs, thereby enhancing the photo-catalytic activity. [ABSTRACT FROM AUTHOR]

C 3 N 4 shows great potential for photo (electro)catalytic hydrogen production from water splitting. Elemental doping can modulate the band structure of C 3 N 4 , thereby broadening the responsive wavelength range, and facilitating charges' separation on C 3 N 4. In this work, phosphorus was doped into C 3 N 4 (PCN) using diammonium hydrogen phosphate as a precursor. Platinum nanoparticles were further photodeposited onto the surface of PCN. With these modifications, the photocatalytic activity in hydrogen production on C 3 N 4 was increased from none to 5.9 μmol/h/g cat after phosphorus doping, and then to 312.5 μmol/h/g cat after Pt loading. Furthermore, C 3 N 4 was grown on carbon cloth, its photoelectrocatalytic activity in hydrogen production was increased from 23.98 to 356.73 mmol/h/m2 after doping with P, and further increased to 400.39 mmol/h/m2 after loading with Pt. The increase in hydrogen production rate could be attributed to the fact that doping with P elements increased the specific surface area of C 3 N 4 , exposing more active sites in C 3 N 4. And the loading of Pt nanoparticles accelerated charges' transfer and separation, thus promoting the catalytic activity. The present study shows that the modification of C 3 N 4 by doping with non-metals and loading metals plays an important role in improving the photo (electro)catalytic performance of C 3 N 4. • Pt, P co-modified C 3 N 4 has been successfully prepared. • Photoelectrocatalytic activity in H 2 production was improved to 400.39 mmol/h/m2. • The reaction mechanism of the great improvement has been explored and discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] The conversion of CO 2 into syngas, a mixture of CO and H 2 , via photocatalytic reduction, is a promising approach towards achieving a sustainable carbon economy. However, the evolution of highly adjustable syngas, particularly without the use of sacrifice reagents or additional cocatalysts, remains a significant challenge. In this study, a step-scheme (S-scheme) 0D ZnGa 2 O 4 nanodots (∼7 nm) rooted g-C 3 N 4 nanosheets (denoted as ZnGa 2 O 4 /C 3 N 4) heterojunction photocatalyst was synthesized vis a facial in-situ growth strategy for efficient CO 2 -to-syngas conversion. Both experimental and theoretical studies have demonstrated that the polymeric nature of g-C 3 N 4 and highly distributed ZnGa 2 O 4 nanodots synergistically contribute to a strong interaction between metal oxide and C 3 N 4 support. Furthermore, the desirable S-scheme heterojunction in ZnGa 2 O 4 /C 3 N 4 efficiently promotes charge separation, enabling strong photoredox ability. As a result, the S-scheme ZnGa 2 O 4 /C 3 N 4 exhibited remarkable activity and selectivity in photochemical conversion of CO 2 into syngas, with a syngas production rate of up to 103.3 μ mol g−1 h−1, even in the absence of sacrificial agents and cocatalyst. Impressively, the CO/H 2 ratio of syngas can be tunable within a wide range from 1:4 to 2:1. This work exemplifies the effectiveness of a meticulously designed S-scheme heterojunction photocatalyst for CO 2 -to-syngas conversion with adjustable composition, thus paving the way for new possibilities in sustainable energy conversion and utilization. [ABSTRACT FROM AUTHOR]

In this study, C 3 N 4 was prepared using the polycondensation method, and TiO 2 (ansate/Brookite) was synthesized using the solvothermal method. These materials were subsequently utilized to prepare C 3 N 4 /TiO 2 heterojunction materials via the photoanchoring method, with the aim of improving photocatalytic hydrogen production. The physical, chemical, and optical properties of the composites were investigated to verify the formation of heterojunctions, as well as to assess the impact of varying levels of C 3 N 4 content (1%, 5%, and 10%) in the C 3 N 4 /TiO 2 composite on hydrogen production. Notably, the composite with 5% C 3 N 4 demonstrated superior photocatalytic hydrogen production (approximately 692 μmol h-1 g-1), and the underlying reasons were elucidated using photoelectrochemical characterization. To establish the band alignment of C 3 N 4 and TiO 2 before and after contact, a comprehensive array of techniques was employed, encompassing Kelvin force microscopy to acquire work functions, UV–Vis spectral analysis to ascertain band gaps, XPS valence spectra to identify the Valence Band Maxima, and the Kraut method to calculate Band Offsets. These analyses revealed that the formation of the heterojunction is staggered in nature. Finally, utilization of ESR analysis has conclusively verified that the charge transfer mechanism inherent in the C 3 N 4 /TiO 2 heterojunction adheres to the Z-scheme. [ABSTRACT FROM AUTHOR]

Photocatalysis is a clean, cost-effective and time-efficient method for degradation of organic pollutants and also other usages such as CO2 photoreduction. In this field, the development of suitable photocatalysts that can be active under visible light irradiation has received much attention and research. To achieve this goal, making photocatalysts with a suitable bandgap can be effective. By combining several suitable materials and making nanocomposites, this goal can be achieved. However, the synthesis method, particle size, surface area and crystallinity can be effective on the photocatalytic properties of the nanocomposites. C3N4 is a low-cost material with good photoactivity properties. Also, this material is thermally and chemically stable. Zinc oxide also is a non-toxic, cost-effective and available photocatalyst. But some limitations such as wide band gap led to decreasing the visible light photoactivity of zinc oxide and also carbon nitride materials. Coupling an organic material like C3N4 with inorganic zinc oxide causes a heterojunction material with interesting properties in degradation of various organic pollutants such as in pesticides and organic dyes. This review accounts with ZnO-doped C3N4 heterostructure and advance methods of construction, photocatalytic efficiency, recycling stability and the mechanism of photodegradation. The photoactivity of ZnO–C3N4 nanocomposite is higher than ZnO and C3N4 nanomaterials. Moreover, modification of the ZnO–C3N4 nanocomposite with doping other metals such as Al, Mg, Ni, Cu, Ag significantly improves the photoactivity. The mechanism of photodegradation of this nanocomposite can be based on photo-oxidation and also photoreduction mechanism. Based on photoreduction mechanism this nanocomposite can be applied to CO2 photoreduction. [ABSTRACT FROM AUTHOR]

In this work we present a computational study of the nature of a Single Atom Catalyst (SAC) consisting of a Pt1 atom anchored on a C3N4 support, and of its reactivity in the water splitting semi-reactions, the Hydrogen Evolution (HER) and Oxygen Evolution (OER) Reactions. The work is motivated by the intense research in designing catalytic materials for water splitting characterized by a low amount of noble metal species, maximization of active phase, and stability of the catalyst. C3N4-based SACs are promising candidates. The results indicate that the chemistry of a single atom is complex, as it can be anchored to the support in different ways resulting in a different stability. The reactivity of the most stable structure in HER and OER has been considered, finding that Pt1@C3N4 is more reactive than metallic platinum. Furthermore, unconventional but stable intermediates can form that differ from the intermediates usually found on extended catalytic surfaces. The work highlights the importance of considering the complex chemistry of SACs in view of the analogies existing with coordination chemistry compounds. [ABSTRACT FROM AUTHOR]

BACKGROUND: C3N4 nanosheets with a layered structure have attracted significant interest in the field of photocatalysis. However, direct preparation of these nanosheets remains a significant challenge. RESULTS: In this study, highly active C3N4 nanosheets were fabricated via the direct thermal polymerization of melamine supramolecular aggregates obtained using hydrochloric‐acid‐induced hydrothermal pretreatment. Various methods were adopted to characterize the photocatalytic materials obtained and density functional theory calculations were performed to understand the highly efficient nature of C3N4. The structures and photochemistry of the photocatalytic materials depend on the hydrochloric‐acid‐induced hydrothermal pretreatment method. It was found that C3N4‐180‐H nanosheets have numerous (C)2N–H that are conducive to photogenerated electron–hole separation. In addition, the C3N4‐180‐H nanosheets have a large surface area and a short charge‐carrier diffusion distance. Furthermore, the C3N4‐180‐H nanosheets exhibited a longer excitation‐state charge‐carrier lifetime than bulk C3N4. The as‐prepared C3N4‐180‐H nanosheets with unique structural advantages showed superior photocatalytic H2 evolution performance (413 μmol h−1 g−1) compared to that of bulk C3N4 (90.5 μmol h−1 g−1). CONCLUSION: This study offers a feasible and simple method for synthesizing C3N4 nanosheets and developing an excellent 2D photocatalyst for superior solar‐to‐H2 production. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exfoliated graphitic carbon nitride (eg‐C3N4) material was applied as a support to load cobalt catalysts (CoOx/eg‐C3N4) through a simple impregnation method. The physical and chemical properties of the synthesized CoOx/eg‐C3N4 materials were characterized by a series of analytic techniques including XRD, SEM, FT‐IR, UV–vis, and XPS. The characterization results revealed that the introduction of Co2+ species had not altered the graphitic structure of eg‐C3N4. The Co2+ species probably coordinatively interact with the nitrogen‐containing group of eg‐C3N4. The catalytic performances of the CoOx/eg‐C3N4 were evaluated in the solvent‐free selective oxidation of ethylbenzene (EB) using molecular oxygen as an oxidant. Among the 3CoOx/eg‐C3N4 materials with various preparation temperatures, 3CoOx/eg‐C3N4‐400 exhibited the highest EB conversion, which was owing to its superior percentages of Co2+ and tertiary nitrogen species. [ABSTRACT FROM AUTHOR]

One of the materials that has recently been used to remove environmental pollution from industrial effluents with photocatalytic technology is cobalt chromate (CoCr2O4) nanoparticles. An effective way to improve the photocatalytic properties of materials is to composite them with other photocatalysts to prevent recombination of electron-holes and accelerate the transfer of oxidation/reduction agents. Graphitic carbon nitride (g-C3N4) is an excellent choice due to its unique properties. In this research, CoCr2O4 and its composite with g-C3N4 (5, 10, and 15%) were synthesized by polyacrylamide gel method and characterized by X-ray diffraction, scanning electron microscopy, FTIR, UV–Vis spectroscopy techniques. The photocatalytic behavior of synthesized nanoparticles was investigated in the degradation process of methylene blue dye. The results showed that the composite samples have higher efficiency in photocatalytic activity than the pure CoCr2O4 sample. Using CoCr2O4-15 wt%g-C3N4 nanocomposite, after 80 min, methylene blue was completely degraded. The mechanism of degradation by CoCr2O4-g-C3N4 nanocomposite was the superoxide radical produced by the reaction of electrons with oxygen absorbed on the catalyst surface, as well as optically produced holes directly. [ABSTRACT FROM AUTHOR]

The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance. However, owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers, the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells, which leads to unsatisfactory activity. In this paper, a single-atom Co-doped C3N4 photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine. Under a tiny external magnetic field (24.5 mT), the hydrogen production rate could reach at 3979.0 µmol·g−1·h−1, which is about 340 times that of C3N4. Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C3N4, resulting in an increase in dielectric constant and spin polarization. Moreover, magnetic fields further promote parallel electron spin, and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field. On the other hand, the Co-N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction. This work not only deepens the understanding of spin polarization, but also enriches methods to accelerate electron-hole separation. [ABSTRACT FROM AUTHOR]

Artificial photosynthesis is a promising strategy for converting carbon dioxide (CO2) and water (H2O) into fuels and value‐added chemical products. However, photocatalysts usually suffered from low activity and product selectivity due to the sluggish dynamic transfer of photoexcited charge carriers. Herein, we describe anchoring of Ag single atoms on hollow porous polygonal C3N4 nanotubes (PCN) to form the photocatalyst Ag1@PCN with Ag−N3 coordination for CO2 photoreduction using H2O as the reductant. The as‐synthesized Ag1@PCN exhibits a high CO production rate of 0.32 μmol h−1 (mass of catalyst: 2 mg), a high selectivity (>94 %), and an excellent stability in the long term. Experiments and density functional theory (DFT) reveal that the strong metal–support interactions (Ag−N3) favor *CO2 adsorption, *COOH generation and desorption, and accelerate dynamic transfer of photoexcited charge carriers between C3N4 and Ag single atoms, thereby accounting for the enhanced CO2 photoreduction activity with a high CO selectivity. This work provides a deep insight into the important role of strong metal–support interactions in enhancing the photoactivity and CO selectivity of CO2 photoreduction. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing highly efficient and stable photocatalysts remains a major challenge for the remediation of environmental pollutants. In this work, the Bi0 decorated BiOI-Bi 2 O 3 /C 3 N 4 heterojunction (Bi@BiOI-Bi 2 O 3 /C 3 N 4) film was fabricated through ultrasonic stripping, I− etching and in situ UV-reduction processes and then characterized thoroughly by various analytical techniques. The characteristics of simultaneous mitigation of phenol and Cr(VI) were evaluated over Bi@BiOI-Bi 2 O 3 /C 3 N 4 photoanode under visible light. The results exhibited that both phenol and Cr(VI) were removed completely by the photoanode at 2.5 V within 1.5 h, superior to our previous report. The synergy of the surface plasmon resonance (SPR) effect of Bi0 and ternary heterojunction accelerated the separation and transfer of photo-induced charge carrier and thus heavily promoted the removal efficiency. Moreover, the excellent stability of this photoanode was hold with no considerably activity attenuation after 4 cycles. Finally, a dual Z-scheme charge transfer process was presented. This work offers an attractive pathway to construct highly active photoelectrode with promising application for simultaneous remediation of organics and heavy metals in wastewater. [ABSTRACT FROM AUTHOR]

A novel photoelectrocatalytic oxidative desulfurization (PEODS) process by using BiVO4@C3N4 composites deposited on fluorine tin oxide glass as a catalyst is designed. Accordingly, g-C3N4 and BiVO4@C3N4 composite with different amounts of BiVO4 (72%, 56%, and 39%) were prepared and used in a biphasic system. Also, photocatalytic oxidative desulfurization (PODS) and electrocatalytic oxidative desulfurization (EODS) systems are studied and compared to PEODS. The BiVO4@C3N472 (72% BiVO4) sample showed the best results compared to other composites in PODS. The visible-light sensitivity of the photocatalysts was investigated. This system was studied under different reaction conditions such as reaction times, temperatures, amounts of the oxidizing agent, extractants, catalyst amounts, and solvents. By optimizing the reaction parameters, DBT removal reached 91%, 54%, and 75% for PEODS, EODS, and PEODS, respectively. The stability of the catalyst was investigated by recycling the catalyst at four successive reactions with the same efficiency. By the addition of radical scavengers, the mechanism of the reaction was studied and the desulfurization decreased to 67%, 72%, and 64% for BQ, EDTA, and isopropanol, respectively. [ABSTRACT FROM AUTHOR]

Accelerating the charge transfer (CT) capability of photocatalysts is an efficient way to improve the overall photocatalytic performance, yet the precise regulation of CT in photocatalyst systems is still lacking. In this paper, a series of hybrid photocatalysts composed of graphitic carbon nitride (CN) and various viologens (V) were prepared for the photocatalytic hydrogen evolution (PHE) from water splitting under visible-light irradiation. Considering the fixed energy structure of CN , the different electron-withdrawing substituents were introduced to engineer the band structure of V delicately and modulate the CT process between CN and V. It was shown that all the hybrid photocatalysts CN-x%V y exhibited higher photocatalytic performance, of which CN–1%V 3 , possessing the strongest electron withdrawing group (-NO 2), demonstrated the best PHE performance (3572.3 μmol g−1 h−1), exceeding 29 times over the unmodified CN. It was proposed that the introduction of V can optimize the interfacial photogenerated electron transfer (CN → V →Pt) of the whole photocatalytic system effectively. We highlighted the V as an efficient chemical segment to modify semiconductors toward enhanced activity due to the following unique characteristics: (i) the unique redox ability, (ii) the easy synthetic methods for controlling the band structures precisely, and (iii) the inherent positively charged feature. This work provides a deep understanding of CT for the rational design of high-performance photocatalysts through band engineering. [Display omitted] • Hybrid photocatalysts CN-x%V y composed of g -C 3 N 4 (CN) and viologens (V) were prepared. • The photocatalytic performance of CN-x%V y catalysts was dependent on the band engineering of V. • Charge transfer of CN-x%V y catalysts was precisely regulated. • CN–1%V 3 exhibited a 29 times higher photocatalytic H 2 evolution rate than the unmodified CN. [ABSTRACT FROM AUTHOR]

Construction of Z -scheme graphitic carbon nitride-titanium dioxide nanotubes (C 3 N 4 -TNT) has been known useful to optimize the band structure for improving photon capture and for accelerating charge carrier separation and transfer rate in photoelectrochemical water splitting (PECWS) cells. However, the reported operating potential window in a PECWS cell, often in 0 – 1.23 V RHE (volt versus reversible hydrogen electrode) plus its overpotential, is too narrow to understand the C 3 N 4 -TNT electrode. Herein, a broad potential window of −0.5 − 2.5 V RHE is applied to C 3 N 4 -TNT@Ti and recorded via the polarization test under chopped sunlight to analyze the effect of both electrons from external electrical circuit and photons from simulated sunlight. In 0 – 2.5 V RHE , the potential enhances the photocurrent density. For example, at 1.6 V RHE , the C 3 N 4 -TNT sample exhibits 1.8-time higher photocurrent density than that of pure TNT. In −0.5 − 0 V RHE , i.e., both samples do not give photo-current response. In addition, for advanced water oxidation/reduction beyond WS to oxygen/hydrogen, a large potential window will be expected. Further, the light capture ability, the charge carrier recombination rate, and the electron flow path through the C 3 N 4 -TNT junction without and with reverse/forward potentials are discussed to elucidate the effect of the applied potential. [Display omitted] • Z scheme graphitic carbon nitride-anodic TiO 2 nanotubes (C 3 N 4 -TNT) is prepared. • Polarization curve of C 3 N 4 -TNT is recorded in a broad potential, −0.5 − 2.5 V RHE. • C 3 N 4 -TNT shows enhanced light absorption and promoted charge carrier separation. • The effect of potential and solar light on C 3 N 4 -TNT is investigated. • The effect of reverse and forward potential on C 3 N 4 -TNT is discussed. [ABSTRACT FROM AUTHOR]

A simple polyacrylamide gel method combined with low temperature sintering technology has been used to synthesize the C–O functional groups grafted MgAl2O4/C3N4/YMnO3 (MAO–CN–YMO) heterojunction photocatalysts with enhanced visible‐light‐induced photodegradation toward oxytetracycline hydrochloride (OTC‐HCl). A variety of characterization methods are used to gain insight into the phase purity, crystal structure, microstructure, functional group information, elemental composition, surface defect, light response capability, and photocatalytic activity of the as‐synthesized samples. The influences of the mass ratios of mCN/mYMO, mCN/mMAO, and mMAO/(mCN + mYMO) in CN–YMO, CN–MAO, and MAO–CN–YMO heterojunction photocatalysts on the photocatalytic activity for the degradation of OTC‐HCl was also discussed, and the optimal mass ratio of mMAO/(mCN + mYMO) is identified as 15 wt%. The photocatalytic experiments confirmed that the MAO–CN–YMO heterojunction photocatalysts had high selectivity for the degradation of antibiotics. The prediction of the photocatalytic activity of the MAO–CN–YMO heterojunction photocatalysts for the degradation of OTC‐HCl was made by a variety of intelligent algorithm models. The results of the whale optimization algorithm are highly consistent with the experimental results. Combined with the energy band theory and the characterization results of high‐performance liquid chromatography–tandem mass spectrometry, the free radicals in the reaction solution preferentially attacked the –CH3, –NCH2, and –OH of OTC‐HCl during the degradation of OTC‐HCl by MAO–CN–YMO heterostructure photocatalysts, and then attack –C=O and –C=O–NH2, and finally perform ring‐opening reaction to degrade OTC‐HCl into nontoxic and harmless products of small molecules such as CO2, H2O, and NH4+. This work provides a new idea for the development of novel double p–n junction MAO–CN–YMO heterojunction photocatalysts for antibiotic degradation and the prediction of photocatalytic activity of multiple heterojunction photocatalysts by intelligent algorithms. [ABSTRACT FROM AUTHOR]

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Retaining the ultrathin structure of two‐dimensional materials is very important for stabilizing their catalytic performances. However, aggregation and restacking are unavoidable, to some extent, due to the van der Waals interlayer interaction of two‐dimensional materials. Here, we address this challenge by preparing an origami accordion structure of ultrathin two‐dimensional graphitized carbon nitride (oa‐C3N4) with rich vacancies. This novel structured oa‐C3N4 shows exceptional photocatalytic activity for the CO2 reduction reaction, which is 8.1 times that of the pristine C3N4. The unique structure not only prevents restacking but also increases light harvesting and the density of vacancy defects, which leads to modification of the electronic structure, regulation of the CO2 adsorption energy, and a decrease in the energy barrier of the carbon dioxide to carboxylic acid intermediate reaction. This study provides a new avenue for the development of stable high‐performance two‐dimensional catalytic materials. [ABSTRACT FROM AUTHOR]

Hydrogen, as an important clean energy source, is difficult to store and transport, which hinders its applications in real practice. Developing robust yet affordable storage media remains to be a challenge for scientists. In this study, Ab Initio Molecular Dynamics (AIMD) simulations were employed to evaluate the performance of aluminum (Al) decorated carbon nitride (g-C3N4, heptazine structure) in hydrogen storage; and a benchmarking study with Mg-doped g-C3N4 was also performed to provide theoretical insights for future study. We found that each 2 × 2 supercell can accommodate four Al atoms, and that partial charge from single Al sites can be transferred to adjacent nitrogen atoms of g-C3N4. These isolated Al sites tend to be electronically positive charged, serving as active sites for H2 adsorption, predominately by triggering enhanced electrostatic interactions. The H2 molecules are adsorbed by both Al and N atoms, and are easily polarized, giving rise to electrostatic interactions between the gas molecules and the surface. Effective adsorption sites were determined by electronic potential distribution maps of the optimized configurations. Each 2 × 2 supercell can adsorb up to 36 H2 molecules, and the corresponding adsorption energies are within the range of −0.10 to −0.26 eV. The H2 storage capacity of the Al-decorated g-C3N4 is 7.86 wt%, which surpasses the goal of 5.5 wt%, set by the US department of energy. This proposed Al-decorated g-C3N4 material is therefore predicted to be efficient for hydrogen storage. This work may offer some fundamental understandings from the aspect of electronic sharing paradigm of the origin of the excellent hydrogen storage performance by metal decorated 2D materials, acting as an demonstration for guiding single metal atom site-based materials' designing and synthesis. [ABSTRACT FROM AUTHOR]

A colorimetric sensing method for alkaline phosphatase detection is developed using the self-deposited ultrasmall Ru nanoparticles on carbon nitride as peroxidase-like nanozyme. [Display omitted] Carbon nitride (C 3 N 4) nanosheets are known as peroxidase mimics, but the low activity hinders their further application. Embedding active metal nanoparticles onto the C 3 N 4 nanosheets is expected to break this limitation. Herein, highly dispersed ultrasmall Ru nanoparticles are anchored onto the C 3 N 4 through spontaneous redox reaction. The as-obtained Ru-C 3 N 4 exhibits excellent peroxidase-like activity, which can be further regulated by adjusting the loading of Ru nanoparticles on C 3 N 4. Using Ru-C 3 N 4 as a mimetic peroxidase, a colorimetric sensing method for alkaline phosphatase (ALP) detection is developed based on the inhibitory effect of ascorbic acid produced by hydrolysis of ALP and l -ascorbic acid 2-phosphate (AAP) on the color development reaction of TMB catalyzed by Ru-C 3 N 4. The sensor exhibits wide linear range and low detection limit for the ALP sensing. Finally, the assay is applied to ALP detection in human serum and satisfactory results are obtained, which provides a promising strategy for colorimetric sensing of ALP. [ABSTRACT FROM AUTHOR]

Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass waste valorization. The process could be scaled up to obtain hydrogen under natural sunlight irradiation, and research on polymeric carbon nitride (g-C3N4)-based photocatalysts has been widely carried out in recent years. The non-metallic-based carbon nitride materials are economical and (photo)stable polymer semiconductors, and their physicochemical surface and electronic properties are optimal for obtaining H2, which can be considered a gas that does not cause major environmental problems. Some hindrances related to their structure, such as the low absorption of visible light and the relatively high recombination rate of electron-hole pairs, restrict the performance; therefore, it is necessary to improve their activity and the yield of the reaction by modifying them in various ways. Various types of solutions have been proposed in this regard, such as, for example, their coupling with other semiconductors to form composite materials. The current mini-review aims to overview the PR field, reporting some of the most interesting papers devoted to understanding the role of g-C3N4 in biomass PR. Information on many physico-chemical aspects related to the performance of the process and possible ways to obtain better results than those present up to now in the literature will be reported. [ABSTRACT FROM AUTHOR]

In this study, we have successfully developed a layered, porous anode-electrolyte integrated flexible solid-state zinc-air battery (ZAB) using a Zn/C 3 N 4 -CNT/PVA-ER composite. The solid electrolyte is synthesized by incorporating epoxy resin (ER) into PVA, and its morphology, microstructure, mechanical properties, and water absorption/retention capabilities are thoroughly characterized. The resulting PVA-ER solid electrolyte exhibits a porous, oriented structure with excellent mechanical properties, including a tensile strain of 170 % and a stress of 0.37 MPa. It also shows remarkable resilience, withstanding various deformations such as compression, bending, and twisting, along with a high-water absorption capacity of 223.5 g g−1 and a high OH− conductivity of 58.5 mS cm−1. The C 3 N 4 -carbon nanotube (CNT) composite membrane is successfully prepared and applied as the anode, forming efficient ion diffusion channels through cross-linking with PVA-ER chains. The flexible ZABs based on Zn/C 3 N 4 -CNT/PVA-ER demonstrated outstanding performance, including a long operational life of over 74 h, a high-power density of 112.6 mW cm−2, and a specific capacity of 770.8 mAh g−1. This work introduces innovative in-situ crosslinking and electrode-electrolyte integration strategies, advancing the development of high-performance flexible ZABs and paving the way for their application in wearable electronics and biologically inspired systems. [Display omitted] • Introduced in-situ crosslinking for advanced wearable zinc-air batteries. • PVA-epoxy resin (ER) electrolyte offers high tensile strength and ion conductivity. • C 3 N 4 -carbon nanotube (CNT) anode provides efficient ion diffusion and robust flexibility. • Developed flexible zinc-air batteries using Zn/C 3 N 4 -CNT/PVA-ER composite. • Achieved high-power density of 112.6 mW cm−2 and specific capacity of 770.8 mAh g−1. [ABSTRACT FROM AUTHOR]

Fluoride contamination has emerged as a significant global environmental concern, with prolonged consumption of fluoride-rich groundwater being a primary contributor to fluorosis. Nitrogen sites play an important role in the process of fluoride removal, but the influence of different nitrogen species on fluoride adsorption has not been clearly clarified. In this study, a lanthanide organic framework adsorbent La-MOF-NH 2 was prepared by solvothermal method, and a new adsorbent La-MOF-NH 2 @g-C 3 N 4 was synthesized by adding g-C 3 N 4 rich in various nitrogen sources. The effects of adsorbent dosage, pH, temperature and co-existing anions on the adsorption of fluorine were systematically studied. Optimal conditions were identified at a dosage of 2 g/L and a pH of 3, achieving theoretical maximum adsorption capacities of 219.4406 mg/g and 63.1401 mg/g, respectively. The results of five regeneration experiments shown that La-MOF-NH 2 and La-MOF-NH 2 @g-C 3 N 4 have strong recovery capacity. According to the adsorption isotherm and kinetic model, the adsorption mechanism of fluoride ions is mainly hydrogen bonding and chemisorption. In addition, through the experimental characterization and mechanism study, it was proved that amino group > pyridinic nitrogen > graphitic nitrogen. It provides a good guide for designing adsorbents containing nitrogen sites. [Display omitted] • After five cycles of regenerations, the adsorption capacity remained at 60 %. • The adsorption capacities of La-MOF-NH 2 and La-MOF-NH 2 @g-C 3 N 4 were up to 219.44 mg/g and 63.14 mg/g. • The effects of different nitrogen species on fluoride adsorption were investigated. • The adsorption mechanism of fluoride ion was mainly hydrogen binding and chemisorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • The R ct value of Ti 4 O 7 -C 3 N 4 (5.445 Ω·cm2) was reduced by 66.05 % compared with Ti 4 O 7. • The degradation ratio of IMD with Ti 4 O 7 -C 3 N 4 was as high as 99.18 % in 1.256 min. • The removal of IMD in the actural Wanjiang water with Ti 4 O 7 -C 3 N 4 was up to 81.12 %. Imidacloprid (IMD) is a kind of neonicotinoid insecticide, which is widely used in the agricultural production. There are few reports on electrocatalytic degradation of IMD with the low concentration. In this study Ti 4 O 7 -C 3 N 4 electrode was employed for the first time to electrocatalytically degrade low concentration IMD. Compared with pure Ti 4 O 7 electrode, the oxygen evolution potential was increased from 1.84 V to 2.50 V, the charge transfer resistance (R ct) was reduced by 66.05 %, and the oxygen vacancies were increased by 2.5 times compared to the original Ti 4 O 7. Especially, the R ct for Ti 4 O 7 (5.45 Ω·cm2) was only 1/7 of that for boron-doped diamond (BDD) (38.89 Ω·cm2). IMD degradation ratio was up to 98 % in only 1.256 min (75.360 s) using a Ti 4 O 7 -C 3 N 4. When SongShan Lake water, Wanjiang water, and secondary effluent were treated, the degradation radios of IMD were 70.30 %, 72.33 % and 81.12 %, respectively. In the presence of Cl− coexisting ions, no disinfection by-product of ClO 4 − was detected, which is an advantage for Ti 4 O 7 -C 3 N 4 compared with BDD. The first and 48th degradation ratios were 99 % and 97 %, respectively, indicating the good stability of Ti 4 O 7 -C 3 N 4. The development of Ti 4 O 7 -C 3 N 4 provides a stable, low energy consumptions and no secondary pollution anode for the treatment of actual wastewater. [ABSTRACT FROM AUTHOR]

Based on the random method combining with group and graph theory (RG2), a new chiral (P3 2 21) framework is discovered, which can be considered as the second crystalline allotrope of C 3 N 4 with mixed sp2 and sp3 bonding features similar to the previously synthesized P4 3 2 1 2 phase [ Physical Review B, 94, 094,106, 2016 ]. P3 2 21 is both dynamically and mechanically stable, and it is energetically more favorable than the superhard and dense α-phase and β-phase at ambient conditions. The calculated band structures show that P4 3 2 1 2 and P3 2 21 are indirect band gap insulators with energy gaps of 3.452 eV and 3.542 eV and their Vicker's hardness are confirmed to be 10. 98 GPa and 22.79 GPa, respectively. It is interesting that the simulated E-P and E-V curves show that P3 2 21 will be more favorable than P4 3 2 1 2 after 19 GPa and it possesses an opportunity to survive within a certain volume interval. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Retaining the ultrathin structure of two‐dimensional materials is very important for stabilizing their catalytic performances. However, aggregation and restacking are unavoidable, to some extent, due to the van der Waals interlayer interaction of two‐dimensional materials. Here, we address this challenge by preparing an origami accordion structure of ultrathin two‐dimensional graphitized carbon nitride (oa‐C3N4) with rich vacancies. This novel structured oa‐C3N4 shows exceptional photocatalytic activity for the CO2 reduction reaction, which is 8.1 times that of the pristine C3N4. The unique structure not only prevents restacking but also increases light harvesting and the density of vacancy defects, which leads to modification of the electronic structure, regulation of the CO2 adsorption energy, and a decrease in the energy barrier of the carbon dioxide to carboxylic acid intermediate reaction. This study provides a new avenue for the development of stable high‐performance two‐dimensional catalytic materials.

[Display omitted] • On Single Atom Catalysts (SACs) the Oxygen Evolution Reaction (OER) does not necessarily occur via formation of classical intermediates, as usually assumed. • The OER process can follow non-classical paths where the formation of new intermediates takes place: OH* OH*, OH* O*, O* O* and O 2 * complexes. • 30 catalysts based on graphene, nitrogen doped graphene and carbon nitride have been analysed, and in all cases at least one unconventional intermediate was found to be more stable than the classical ones. The Oxygen Evolution Reaction (OER) is a key part of water splitting. On metal and oxide surfaces it usually occurs via formation of three intermediates, M(OH), M(O), and M(OOH) (also referred to as OH*, O*, and OOH* species where * indicates a surface site). The last step consists of O 2 release. So far, it has been generally assumed that the same path occurs on single atom catalysts (SACs). However, the chemistry of SACs may differ substantially from that of extended surfaces and is reminiscent of that of coordination compounds. This raises the question of whether on SACs the OER follows the classical mechanism or not. Using a DFT approach, we studied a set of 30 SACs made by ten metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Pd and Pt) anchored on three widely used 2D carbon-based materials, graphene, nitrogen-doped graphene and carbon nitride. In none of the cases examined the most favourable reaction path is the conventional one. In fact, in all cases other intermediates with higher stabilities form: M(OH) 2 , M(O)(OH), M(O) 2 , and M(O 2) (OH* OH*, O* OH*, O* O*, O 2 * according to standard nomenclature). Therefore, the common assumption that on SACs the OER proceeds via formation of OH*, O*, and OOH* intermediates is not verified. Predictions of new catalysts based on the screening of large number of potential structures can lead to completely incorrect conclusions if these additional intermediates are not taken into consideration. [ABSTRACT FROM AUTHOR]

The interfacial charge transfer control is a key and arduous issue for propelling the migration/separation of photogenerated carriers for heterojunction photocatalysts. Here, a new 2D/2D C 3 N 4 /C 3 N 5 nonmetal van der Waals (VdW) heterojunction is fabricated by the simple self-assembly technique in acidic medium, whose charge separation efficiency is promoted dramatically, thus being endowed with the high-efficiency photocatalytic hydrogen evolution (PHE) performance. The PHE rate reaches up to 3.33 mmol h−1 g−1 under the visible light and the apparent quantum efficiency (AQE) of 20.6% is achieved at 420 nm on the optimal 2D/2D C 3 N 4 /C 3 N 5 -5% sample. Furthermore, the 2D/2D C 3 N 4 /C 3 N 5 nonmetal VdW heterojunction also exhibits the desired stability because there was no significant decrease after PHE reaction of 10 cycles with total 40 h. Such outstanding PHE activity and stability originate from the impelled separation of photoinduced charge carriers and the powerful interfacial interaction through forming Z-Scheme charge transfer path and π-π coupling effect between C 3 N 4 and C 3 N 5 nanosheets. This work takes a significant guiding and demonstration for designing and exploiting other novel nonmetallic polymer-based VdW heterojunctions in the photocatalytic application field. [Display omitted] • 2D/2D C 3 N 4 /C 3 N 5 nonmetal VdW heterojunction was fabricated by self-assembly technique. • AQE of 20.6% is achieved at 420 nm for the PHE reaction. • Heterojunction with superior stability can endure 10 cycle runs with total 40 h. • The superior PHE activity derives from the formed Z-Scheme mechanism. [ABSTRACT FROM AUTHOR]

Hierarchically porous CNT@NC@GCN membranes with high porosity of 85% are fabricated facilely, the 3D hierarchical porous network can provide broad reaction interface and active sites for LiPSs anchoring. Furthermore, the uniform GCN layer can significantly improve the metallicity and conductivity of the frameworks, and strengthen Li+ and electron transport. The abundant N in the GCN coating can enrich active sites in the membrane for adsorption and catalysis conversion of LiPSs and Li 2 S at a low energy barrier. [Display omitted] Various challenges remain to be overcome in lithium-sulfur (Li-S) batteries, including the volume expansion and low conductivity of sulfur, the shuttle effect of lithium polysulfides and the sluggish redox reaction in the cell. Herein, we propose a multilayered conductive framework by the in situ growth of a conformal graphene-like C 3 N 4 (GCN) coating on porous CNT@NC networks with carbon nanotubes (CNTs) as the core and N -doped carbon (NC) as the crosslinking shell. The abundant N in the GCN coating increased the surface N concentration of the framework from 14.38% to 18.77%, which enriched the active sites in the frameworks for the adsorption and catalysis conversion of LiPSs and Li 2 S with a low energy barrier. Furthermore, the scalable frameworks can provide an 85% porosity for a sufficient reaction interface and accommodate the volume expansion of sulfur. The synergistic effect between GCN and the highly conductive hierarchical structure can accelerate the transport of Li+ and electrons as well as the diffusion of electrolyte. Benefitting from the above advantages, the Al-free CNT@NC@GCN electrode exhibits a reversible capacity of 647.6 mAh g−1 after cycling for 450 cycles at 1C with a low capacity fading rate of 0.09% per cycle. This proposed facile strategy creates inspiring insights into the design of novel cathode materials for Li-S batteries. [ABSTRACT FROM AUTHOR]