Single g-C3N4 Research Articles

Photocatalytic degradation of sulfamethazine using g-C3N4/TiO2 heterojunction photocatalyst: Performance, mechanism insight and degradation pathway

In the present research, Z-scheme g-C3N4/TiO2 heterojunction composite photocatalysts with varied g-C3N4 content were successfully prepared using the sol-gel technique combined with calcination methods. The morphology, crystallinity, chemical composition, and optical properties of the synthesized catalysts were characterized employing a series of techniques. Sulfamethazine (SMZ) was selected as the model pollutant to evaluate the photocatalytic activity of the prepared catalysts employing a 500 W xenon lamp as the light source to simulate sunlight. The results demonstrated that within 180 min of irradiation, 94.8 % of SMZ was removed by using the optimal photocatalyst (0.4CN/TiO2 composite sample), affording an apparent first-order rate coefficient of 0.0152 min−1 which was 3.8 or 2.0 times as much as that involving single g-C3N4 or TiO2 catalyst, respectively. The effects of catalyst dosage, initial pH, different water matrices, different substrates, and inorganic ions on the performance of 0.4CN/TiO2 photocatalyst were explored. Furthermore, the 0.4CN/TiO2 composite also displayed satisfactory cyclic stability. The results of radical quenching experiments revealed that the key active species in SMZ degradation were hydroxyl radicals (•OH), superoxide radicals (O2•−), and holes (h+). The efficient separation of photo-generated electrons and holes originating in the formation of a Z-scheme g-C3N4/TiO2 heterojunction was evidenced by photoluminescence and electrochemical impedance spectroscopy determination and should be responsible for the enhanced catalytic activity of the 0.4CN/TiO2 sample. In addition, the plausible pathways for the aqueous degradation of SMZ were suggested according to the identified degradation intermediates employing the HPLC/MS technique. In summary, the current research provides a novel insight into the development of Z-scheme heterojunctions in the realm of organic pollutant treatment.

Construction of direct-Z-scheme heterojunction photocatalyst of g-C3N4/Ti3C2/TiO2 composite and its degradation behavior for dyes of Rhodamine B

Direct-Z-scheme g-C3N4/Ti3C2/TiO2 photocatalyst with giant internal electric field were prepared by one-step aqueous sonication self-assembly method using g-C3N4 and MXene of Ti3C2 as the source materials. The chemical composition and structure of the catalysts was characterized by FT-IR, XRD, SEM, TEM and XPS. The XPS characterization indicated that Ti3C2 was partially oxidized to TiO2 during the composite process. As a result, an efficient direct-Z-scheme heterojunction structure consisting of the g-C3N4 and TiO2 with Ti3C2 as an electron bridge was constructed. The photocatalytic performance of the prepared catalysts was evaluated by degrading the rhodamine B (RhB) wastewater. Compared with the single g-C3N4, the g-C3N4/Ti3C2/TiO2 composite photocatalyst exhibited efficient and stable photocatalytic degradation ability, with a degradation efficiency as high as 99.2% for RhB under optimal conditions (2% Ti3C2, pH=3). The high degradation performance of g-C3N4/Ti3C2/TiO2 for RhB was attributed to the combination of Ti3C2, TiO2, and g-C3N4 components, forming a direct-Z-scheme heterojunction with a high-speed electron transport channel structure. The role of Z-scheme heterojunctions in electron transport is verified by photoelectrochemical characterization, along with photoluminescence (PL). Our research provides a simple method to design photocatalysts by constructing direct-Z-scheme electron transport channels for highly efficient treatment of dye wastewater.

When 2D g-C3N4 meets 0D CNQDs and 1D CNTs: A strategy for photocatalytic hydrogen production over a ternary non-metallic catalyst

Utilizing solar energy to facilitate photocatalytic hydrogen production holds great promise in addressing the energy crisis. One material that shows tremendous potential in this field is two-dimensional graphitic carbon nitride (2D g-C3N4). However, the fast recombination rate of photogenerated carriers and the limited specific surface area impede its photocatalytic activity. This research endeavors to address these limitations by developing a ternary composite photocatalyst, CNQDs/g-C3N4/CNTs, by employing the microwave hydrothermal method. g-C3N4 was co-modified with zero-dimensional g-C3N4 quantum dots (0D CNQDs) and one-dimensional carbon nanotubes (1D CNTs). Incorporating CNQDs and the g-C3N4 interface facilitates the separation of photogenerated carriers, while the tubular channel of CNTs provides favorable conditions for transferring photogenerated electrons. Additionally, the introduction of CNQDs and CNTs significantly increases the specific surface area of the sample, thereby enhancing the number of reaction active sites available for the photocatalytic production of hydrogen. The hydrogen generation rate of the CNQDs/g-C3N4/CNTs is 1109.388 μmol⋅g−1⋅h−1, surpassing that of the single g-C3N4 specimen by 3.62 times. The application of density functional theory (DFT) calculations reinforces the enhanced performance of the composite through the synergistic effect of CNQDs and CNTs. This effect optimizes the adsorption behavior of the active intermediate (H*) and reduces the Gibbs free energy ΔG(H*) associated with the photocatalytic hydrogen evolution reaction.

Preparation of Z-type Cu2SnS3/g-C3N4 heterojunction material and its synergistic photocatalytic performance with H2O2

Due to poor visible light responsiveness and easy recombination of photo generated carriers, the photocatalytic performance of a single g-C3N4 is limited. This article presents a Z-type Cu2SnS3/g-C3N4 (CTS/CN) heterojunction photocatalyst prepared by in-situ growth of CTS on the surface of g-C3N4 using a simple solvothermal method. Through SEM results, it can be seen that as the content of g-C3N4 increases, the nanosheet gaps of flower shaped microspheres on the surface of CTS/CN increase and the size becomes thinner. The UV–vis DRS experiment showed that the introduction of CTS increased the visible light absorption range of CTS/CN composite and improved its visible light absorption ability.Under the synergistic effect of H2O2, the photocatalytic degradation efficiency of CTS/70% CN towards MO reached 99% at 50 minutes，At the same time, the degradation rate constants k of methylene blue (MB), ciprofloxacin (CIP) and levofloxacin (LEV) reached 0.06289 min−1, 0.02132 min−1 and 0.02787 min−1 respectively at 100 min.In the synergistic MO system of H2O2 for photocatalytic degradation, free radical capture experiments showed that the main active species were h+and • OH. Combined with the band structure of Cu2SnS3 and g-C3N4, a Z-type photocatalytic mechanism was proposed. Under visible light, H2O2 rapidly captured the photo generated electrons of CTS/CN, promoting the transport of photo generated carriers. This study provides theoretical guidance for the design and construction of Z-type heterojunctions with superior visible light driven photocatalytic performance.

Unique synergistic effects of ternary multi-dimensional CNT/g-C3N4/MoS2 hybrid as a paraffin oil additive for improved tribological properties

Graphitic carbon nitride (g-C3N4) nanomaterials have drawn much interest in the lubrication and friction fields owing to their excellent self-lubrication and mechanical performances. However, the easy agglomeration and poor dispersion stability of single g-C3N4(CN) have always been a headache. In the work, multi-dimensional ternary carbon nanotube, graphite carbon nitride, and molybdenum disulfide (CNT, CN, and MoS2) hybrids were fabricated by hydrothermal method. The microstructure and its reinforcement impact on the tribological properties of the corresponding paraffin oil were systematically studied. The results showed that the zero-dimensional spherical MoS2, one-dimensional tubular CNT, and two-dimensional lamellar CN are uniformly compounded. The tribological test results display that average friction coefficient and wear rate of the 0.2 wt% CNT/CN/MoS2 are decreased by 39.23% and 91.97% lower than those of pure paraffin oil, CNT and CN/MoS2 with the same concentration, respectively. The significantly improved tribological properties of lubricating oil is ascribed to even dispersion of CNT, CN, MoS2 in CNT/CN/MoS2 hybrids, self-lubricating effect of MoS2 and CN, and load-bearing ability of CNT and CN nanosheets, and also the generation of lubricating film between friction pairs during the wear process.

One-Step Synthesis of Alkali Metal-Hydroxyl Double Modified Graphite Phase Carbon Nitride and Photocatalytic Degradation of Phenolic Compounds

In this work, potassium ion-hydroxyl double modified graphite phase carbon nitride (KCN–OH) was synthesized in one step by alkali hydrothermal (AH) method. The as-prepared catalysts were characterized by XRD, FT-IR, UV–Vis, N2 adsorption, SEM, XPS, PL, ESR, TPD and EIS. The introduction of potassium ion causes the reduced crystal size, increased specific surface area and promoted electron–hole separation efficiency of as-prepared catalyst. The hydroxyl group not only further improves the electron–hole separation efficiency but, as the electron donor group, can also make stronger interaction between catalyst and acidic phenolic compounds. The photocatalytic degradation of phenol was investigated under visible light. The results show that the phenol degradation rate constant of KCN–OH is 0.22 h[Formula: see text] under visible light, which is over 3.7 and 2.0 times higher than that of neat g-C3N4 and single hydroxyl-modified g-C3N4. KCN–OH also displays outstanding catalytic and structural stability. The possible reaction mechanism is discussed in this paper.

Enhanced photoelectrochemical water splitting performance of α-Fe2O3 photoanodes through Co-modification with Co single atoms and g-C3N4.

The practical application of α-Fe2O3 in water splitting is hindered by significant charge recombination and slow water oxidation. To address this issue, a CoSAs-g-C3N4/Fe2O3 (CoSAs: cobalt single atoms) photoanode was fabricated in this study through the co-modification of CoSAs and g-C3N4 to enhance photoelectrochemical (PEC) water splitting. The coupling between g-C3N4 and α-Fe2O3 resulted in the formation of a heterojunction, which provided a strong built-in electric field and an additional driving force to mitigate charge recombination. Moreover, g-C3N4 served as a suitable carrier for single atoms, which effectively anchored CoSAs through N/C coordination. The highly dispersed CoSAs provided abundant active sites, which further promoted surface holes extraction and oxidation kinetics, resulting in higher PEC performance and photostability. This study indicates the benefits of these collaborative strategies and provides more efficient designs for solar energy conversion in PEC systems.

Composites of W18O49 Nanowires with g-C3N4/RGO Nanosheets for Broadband Light-Driven Photocatalytic Wastewater Purification.

Developing a photocatalyst that can effectively utilize the full solar spectrum remains a high-priority objective in the ongoing pursuit of efficient light-to-chemical energy conversion. Herein, the ternary nanocomposite g-C3N4/RGO/W18O49 (CN/RGO/WO) was constructed and characterized by a variety of techniques. Remarkably, under the excitation of photon energies ranging from the ultraviolet (UV) to the near-infrared (NIR) region, the photocatalytic performance of the CN/RGO/WO nanocomposite exhibited a significant enhancement compared with single component g-C3N4 or W18O49 nanosheets for the degradation of methyl orange (MO). The MO photodegradation rate of the optimal CN/1.0 wt% RGO/45.0 wt% WO catalyst reached 0.816 and 0.027 min-1 under UV and visible light excitation, respectively. Even under low-energy NIR light, which is not sufficient to excite g-C3N4, the MO degradation rate can still reach 0.0367 h-1, exhibiting a significant enhancement than pure W18O49. The outstanding MO removal rate and stability were demonstrated by CN/RGO/WO nanocomposites, which arise from the synergistic effect of localized surface plasmon resonance effect induced by W18O49 under vis-NIR excitation and the Z-scheme nanoheterojunction of W18O49 and g-C3N4. In this work, we have exploited the great potential of integrating nonmetallic plasmonic nanomaterials and good conductor RGO to construct high-performance g-C3N4-based full-solar spectral broadband photocatalysts.

Synergistic reduction of U(VI) and selective oxidation of benzyl alcohol to prepare benzaldehyde via WOx/g-C3N4

In the photoreduction of U(VI), protective gases and additional sacrificial agents are still the major obstacles. Herein, we developed an oxygen-deficient WOx/g-C3N4 catalyst for the simultaneous reduction of U(VI) and preparation of benzaldehyde by selective oxidation of benzyl alcohol without protective gases and sacrificial agents. The removal of U(VI) by WOx/g-C3N4 could reach 98.5% and the conversion of benzyl alcohol was nearly 32% with a selectivity close to 100%. Compared with single g-C3N4 and defect-free WO3, the photoreduction activity of WOx/g-C3N4 was 10.4 and 7 times higher, respectively. Besides, the role of oxygen and oxygen defects was explored. Owing to oxygen defects in the catalyst, oxygen was adsorbed on the oxidation end (WOx) of the catalyst and activated without entering the reduction end to interfere with the photoreduction of U(VI), while favoring the generation of •O2- to improve the selectivity of benzaldehyde. Finally, a new mechanism was proposed.

Investigation into the performance of Ag2O/g-C3N4 p-n heterojunction photocatalysts with efficient H2 production activity

The use of photocatalysts to break down water into hydrogen (H2) is one of the effective ways to solve energy scarcity and environmental pollution. The light utilization efficiency and separation efficiency of photogenerated carriers are key parameters for their application in photocatalytic H2 production. In this work, direct Z-scheme p-n heterojunction composites consisting of Ag2O and g-C3N4 (Ag2O/CN) were synthesized via an in-situ synthesis method. Characterizations of the synthesized Ag2O/CN composites were conducted to understand the performance of the photocatalysts for H2 production and to elucidate the possible mechanism. The experimental parameters such as Ag2O loading, sacrificial agent and electrolyte condition on photocatalytic H2 production were also investigated. The results show that the Ag2O/g-C3N4 composites have a favorable photoelectric effect and exhibit better H2 evolution performance than the single Ag2O and g-C3N4. The optimum formulation for the Ag2O/CN composites is to use triethanolamine as the sacrificial agent, 0.1 M KOH as the electrolyte, and 3 wt% Ag2O loading (3Ag2O/CN). The highest H2 production of 3Ag2O/CN is 7966.16 μmol/g/h, which is 3.68 and 195.48 times higher than that of g-C3N4 (2165.18 μmol/g/h) and Ag2O (40.75 μmol/g/h), respectively. The direct Z-scheme p-n heterojunction formed by g-C3N4 and Ag2O is the main reason for the enhanced photocatalytic activity. This study provides new ideas for the design of efficient g-C3N4-based p-n heterojunctions.

The Construction of an α-F2O3/Tubular g-C3N4 Z-Scheme Heterojunction Catalyst for the Efficient Photocatalytic Degradation of Tetracycline

Morphological engineering and semiconductor coupling show significant potential to increase the photocatalytic performance of graphite carbon nitride (g-C3N4). In this work, a unique Z-scheme heterojunction photocatalyst composed of tubular g-C3N4 (TCN) and α-F2O3 was successfully synthesized. Combining the experimental results and characterization, we extensively investigated the charge transfer mechanism of the α-F2O3/tubular g-C3N4 (FO-TCN) heterojunctions and processes in the photocatalytic degradation of tetracycline (TC). The tubular morphology provided a larger specific surface area, enhancing the light absorption area and thus improving the exposure of the active sites. Not only was the light absorption range expanded through the coupling with α-F2O3, but the charge transfer properties of the sample were also strengthened. The synergism between photocatalysis and the Fenton reaction enhanced the photocatalytic performance of the FO-TCN. Due to the previously mentioned beneficial factors, the performance of the FO-TCN photocatalyst was significantly increased; its reaction rate k value in the degradation of TC (0.0482 min−1) was 4.05 times faster than that of single g-C3N4 and it exhibited the best photocatalytic performance (95.02%) for the degradation of TC in 60 min, with an enhancement of 38.41%. Quenching experiments showed that h+ and ·O2− were the major active substances in the photocatalytic degradation process.

The Synergistic Lubrication Effects of h-BN and g-C3N4 Nanoparticles as Oil-Based Additives for Steel/Steel Contact.

The synergistic effect of different types of solid particles in liquid lubricants is of great interest. In this work, g-C3N4 nanosheets were initially prepared using a calcination method and then as-prepared, and h-BN were used as lubricating additives to the white oil. A comparison between the mixed additives and the single g-C3N4 or h-BN additives revealed that the base oil with the addition of g-C3N4 and h-BN showed the best lubricating properties. The results show a 12.3% reduction in friction coefficient, resulting in a 68.6% reduction in wear rate compared to the white oil when filled with 0.5 wt% g-C3N4 and h-BN (1:1 by weight). Moreover, the addition of g-C3N4 and h-BN improves the high-temperature lubrication properties of the white oil. However, the friction coefficient and wear rate increase with increasing oil temperature. The large contact area between g-C3N4 and its sliding counterpart and the strong adhesive force between h-BN and its sliding counterpart improve the film formation efficiency, leading to enhanced tribological properties under oil lubrication conditions.

Enhanced photocatalytic hydrogen evolution over Ce–TiO2/graphite/g-C3N4 ternary S-scheme heterojunction

Efficient charge separation is of great significance for achieving high-efficient photocatalytic H2 evolution (PHE) performance. However, charge separation remains a big challenge owing to serious charge recombination in a single photocatalyst material. In this study, we engineered a composited material composed of one-dimensional (1D) cerium (Ce)-doped TiO2/graphite/g-C3N4 (TC/GR/CN) S-scheme ternary heterojunction by using an in-situ tri-coaxial electrospinning method for efficient solar-driven H2 generation. Experimental and theoretical investigations confirmed that the polarization effect of the conductive graphite could strengthen the internal electric field (IEF) to improve the interfacial charge transfer between Ce-doped TiO2 to g-C3N4. The close-contact heterointerfaces and S-scheme charge transfer pathway in the Ce-doped TiO2/graphite/g-C3N4 hybrid could accelerate the separation of photoexcited charge carriers and optimize H* adsorption/desorption properties. Consequently, the Ce-doped TiO2/graphite/g-C3N4 exhibited a superior photocatalytic H2 generation rate of 3.05 mmol·g−1·h−1, which was 38.7 folds higher than those of conventional single g-C3N4 catalyst. This work proposes a facile and controllable electrospinning strategy for designing ideal hydrogen evolution photocatalysts, which may stimulate further studies on developing the advanced catalyst systems.

Construction of Co-doped Sn3O4/g-C3N4 heterojunction with enhanced interface transmission capatibility for improving hydrogen production

In order to alleviate the increasingly serious energy problems, the researches and developments of photocatalysts with efficient solar energy utilization, low price and cost, and long-term stability are the critical problem to expand the application technology of photocatalysis. In this work, Co doped Sn3O4 and g-C3N4 were constructed into an S-scheme Co–Sn3O4/g-C3N4 heterojunction photocatalytic system by simple and feasible solvothermal method for photocatalytic H2 evolution. And different loading amounts of Co–Sn3O4/CN-X were obtained by mean of changing the dosage of Co–Sn3O4. The synthesized photocatalysts represented exceptional H2 evolution performance under visible light irradiation (λ>420 nm), among which Co–Sn3O4/g-C3N4-3 showed the best performance, and the H2 yield reached 1793.88 μmol h−1 g−1. This value was significantly higher than that of single catalysts Sn3O4 (294.82 μmol h−1 g−1) and g-C3N4 (1111.28 μmol h−1 g−1). Moreover, the H2 yield of reused Co–Sn3O4/g-C3N4-3 sample kept above 1737.67 μmol h−1 g−1 during cyclic test. XPS, UV–vis DRS and a series of photoelectrochemical analysis ascertained the establishment of internal electric field and bending of the energy band between the interface of Co–Sn3O4 and g-C3N4, which provided the possibility for Co–Sn3O4 and CN to construct Co–Sn3O4/g-C3N4 S-scheme heterostructure. What's more, the mechanism of producing H2 on the surface of Co–Sn3O4/g-C3N4 by oxidizing H2O was proposed. This work demonstrated the application prospect of reasonably designing g-C3N4 based photocatalysts with exceptional stability, sterling functionality and prominent efficiency for H2 evolution, and provided availed guidance for the research and development of g-C3N4 based photocatalysts.

Construction of S-scheme CdS/g-C3N4 heterojunctions with enhanced photocatalytic H2 evolution and Cr(VI) reduction performance

Construction of heterojunctions is one of the most attractive approaches to synthesize highly active photocatalysts. In this work, we prepared CdS/g-C3N4 (CSCN) heterojunctions with different molar ratio of CdS/g-C3N4 via ball milling for photocatalytic hydrogen production and removal of Cr(VI). The successful construction of CSCN heterojunctions was proved by the various characterization methods. Formation of CSCN heterojunctions not only generates more vacancies to act as active site, but also accelerates the separation of photoinduced charge carriers, endowing with more electrons to participate in the photocatalytic reduction reaction. 2%CSCN sample was confirmed to hold the highest separation and transfer performance of photoinduced e−/h+ pairs by photoelectric tests. 2%CSCN samples exhibit the highest photocatalytic H2 evolution rate (680.04 μmol/g/h), which is 3.63-fold higher than that of the bare g-C3N4 (146.83 μmol/g/h). The activity of photocatalyst was further examined by removal of Cr(VI) experiment. The results show that the reduction efficiency of Cr(VI) on 2%CSCN is 2.46-fold of that of on the single g-C3N4, and the elimination rate of Cr(VI) on 2%CSCN can reach 64% after 1 h under simulated sunlight illumination. The improved photocatalytic performance can be ascribed to the creation of appropriate C vacancies and the widened light absorption range induced by CdS. A rational mechanism for enhanced photocatalytic activity was proposed to further understand the separation and transfer of photogenerated carriers produced by heterojunctions.

Preparation, characterization, and photocatalytic activity of g-C<sub>3</sub>N<sub>4</sub>/SrTiO<sub>3</sub> composite

The g-C3N4/SrTiO3 composite was hydrothermally synthesized at 150 oC for 12 hours from a dispersed mixture of g-C3N4 and SrTiO3 in water, in which SrTiO3 was hydrothermally synthesized at 150 oC for 12 hours using strontium nitrate, propan-2-ol, titanium tetrachloride and sodium hydroxide as precursors without assistance of any surfactant; and g-C3N4 was prepared by pyrolysis of melamine at 520 oC. The properties of materials were characterized by various techniques such as X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS). The photocatalytic activity of materials was assessed by degradation of methylene blue (MB) under visible light. The enhancement of photocatalytic activity of the g-C3N4/SrTiO3 composite compared to single components g-C3N4 and SrTiO3 was observed.

Construction of tubular g-C3N4/TiO2 S-scheme photocatalyst for high-efficiency degradation of organic pollutants under visible light

Graphitic carbon nitride (g-C3N4) is a promising photocatalyst with lots of merits, such as visible light driven (200–1000 nm), cost-effective and high stability. However, the single g-C3N4 photocatalyst is limited in its performance due to the high complexation rate of photogenerated electrons and holes and the confined specific surface area. Herein, a S-scheme heterojunction catalyst involving tubular g-C3N4 (TCN) and TiO2 is designed and constructed via precursor reforming strategy with subsequent hydrothermal calcination process. The tubular structure offers more active centers, conducive to light absorption and contact with pollutants, while the heterojunction facilitates the transfer and separation of electrons and holes. Thus, the TCN/TiO2 catalyst exhibits excellent photocatalytic activity with degradation efficiencies for methylene blue (MB) and tetracycline (TC) reaching 96.6 % and 100 %, respectively, as well as high degradation efficiency for other dyes (Congo red and Eosin y). Besides, TCN/TiO2 catalyst demonstrates outstanding stability and potential for practical application. An innovative S-scheme heterojunction system has shown remarkable potential for improving the separation and transferring electron-hole pairs, as well as delivering stronger redox capability. This work provides a promising strategy for the preparation of g-C3N4/TiO2 catalyst for the effective treatment of contaminated water.

Variable valence Mo5+/Mo6+ ionic bridge in hollow spherical g-C3N4/Bi2MoO6 catalysts for promoting selective visible light-driven CO2 photoreduction into CO

Herein, the catalysts of ultrathin g-C3N4 surface-modified hollow spherical Bi2MoO6 (g-C3N4/Bi2MoO6, abbreviated as CN/BMO) were fabricated by the co-solvothermal method. The variable valence Mo5+/Mo6+ ionic bridge in CN/BMO catalysts can boost the rapid transfer of photogenerated electrons from Bi2MoO6 to g-C3N4. And the synergy effect of g-C3N4 and Bi2MoO6 components remarkably enhance CO2 adsorption capability. CN/BMO-2 catalyst has the best performances for visible light-driven CO2 reduction compared with single Bi2MoO6 and g-C3N4, i.e., its amount and selectivity of CO product are 139.50 μmol g−1 and 96.88% for 9 h, respectively. Based on the results of characterizations and density functional theory calculation, the photocatalytic mechanism for CO2 reduction is proposed. The high-efficient separation efficiency of photogenerated electron-hole pairs, induced by variable valence Mo5+/Mo6+ ionic bridge, can boost the rate-limiting steps (COOH*-to-CO* and CO* desorption) of selective visible light-driven CO2 conversion into CO. It inspires the establishment of efficient photocatalysts for CO2 conversion.

The visible light photocatalytic H2 evolution and degradation enhancement of g-C3N4/Er:CdSe/SiO2 ternary core-shell heterojunction with up-conversion fluorescence auxiliary

The g-C3N4/Er:CdSe/SiO2 ternary core-shell heterojunction with up-conversion fluorescence auxiliary is fabricated via a simple chemical-calcination method. As revealed, the g-C3N4/Er:CdSe/SiO2 ternary core-shell heterojunction (g-C3N4/Er:CdSe/SiO2-3) exhibits remarkable visible light photocatalytic hydrogen evolution and photodegradation tetracycline hydrochloride enhancement than that of single CdSe (∼35 folds of HER, ∼2 folds of photodegradation) and single g-C3N4 (∼70 folds of HER, ∼2 folds of photodegradation), and achieves decent photocatalytic stability. It can be mainly attributed to that, the SiO2 spheres act as optical lens and Er-doping with up-conversion fluorescence can increase solar efficiency, and the formed g-C3N4/Er:CdSe heterojunction with appropriate potential gradient can improve carrier efficiency, including increasing transportation, prolonging lifetime and decreasing recombination. What’s more, the ternary core-shell spheroidal structure can increase active sites and photocatalytic stability.

Transition metal single atom-optimized g-C3N4 for the highly selective electrosynthesis of H2O2 under neutral electrolytes.

Neutral electrosynthesis of H2O2via the 2e- ORR is attractive for numerous applications, but the low activity and high cost of electrocatalysts have become important constraints. Therefore, the development of cheap and efficient electrocatalysts for the 2e- ORR is necessary. Herein, we report the embedding of transition metal single atoms (TM SAs) in g-C3N4 nanosheets (CNNS). The introduction of TM SAs increases the N-CN content and reduces the C-C/CC content in CNNS, which contributes to the increased selectivity of TM SA/CNNS for the 2e- ORR. TM SA is the main reason for the enhanced activity of the 2e- ORR. Based on the results obtained by replacing a series of TM SA, the Ni0.10 SA/CNNS with optimal N-CN content exhibited the best selectivity (∼98%) and highest yield of H2O2 (∼503 mmol gcat-1 h-1), which is ∼14.6 times higher than that of CNNS (∼34.4 mmol gcat-1 h-1). Other TM SA/CNNS also exhibited high activity and selectivity. This study demonstrates the ability of TM SA to modulate the selectivity and activity of CNNS, making it a promising candidate for the 2e- ORR and providing more reference ideas for the preparation of H2O2.