Visible-light-driven photocatalytic degradation of ibuprofen by Cu-doped tubular C3N4: Mechanisms, degradation pathway and DFT calculation

The copper-modified tubular carbon nitride (CTCN) with higher specific surface area and pore volume was prepared by a simple in-situ hydrolysis and self-assembly. Increased ∼4.7-fold and ∼2.3-fold degradation rate for a representative refractory water pollutant (Ibuprofen, IBP) were achieved with low-energy light source (LED, 420 ± 10 nm), as compared to graphitic carbon nitride (GCN) and tubular carbon nitride (TCN), respectively. The high efficiency of IBP removal was supported by narrow band gap (2.15 eV), high photocurrent intensity (1.10 μA/cm2) and the high surface -OH group (14.75 μg/cm3) of CTCN. According to analysis of the various reactive species in the degradation, the superoxide radical (•O2-) played a dominant role, followed by •OH and h+, responsible for IBP degradation. Furthermore, Fukui functions were employed to predict the active sites of IBP, and combined with the HPLC-MS/MS results, possible mechanisms and pathways for photocatalytic degradation were indicated. This study will lay an important scientific foundation and a possible new approach for the treatment of emerging aromatic organic pollutants in visible-light-driven heterogeneous catalytic oxidation environment.

Plasmonic coupling-boosted photothermal nanoreactor for efficient solar light-driven photocatalytic water splitting

Photothermal nanoreactor with rapid charge transfer and improved spectral utilization is a key point in photocatalysis research. Herein, silver sulfide quantum dots (Ag2S QDs) were coating on the surface of porous graphitic carbon nitride nano vesicles (PCNNVs) to form Ag2S/PCNNVs nanoreactors by a simple calcination method for obtaining efficient photothermal-assisted photocatalytic hydrogen (H2) evolution under simulated/real sunlight irradiation. In particularly, the as-prepared optimal 3% Ag2S/PCNNVs sample exhibited the H2 production rate of 34.8 mmol h-1 g-1, which was 3.5 times higher than that of bare PCNNVs. The enhancement of photothermal-assisted activity over the Ag2S/PCNNVs composite system is mainly attributed to the coupling of the photothermal conversion performance of Ag2S QDs and the thermal insulation performance of PCNNVs based on the plasmonic coupling-boosted photothermal nanoreactor. This study presents a promising strategy for the development of high-efficient photothermal-assisted photocatalysts.

Synthesis and Catalytic Degradation of PEF, ENR, and CIP by g-C3N4/TCNQ/Eu Composite

By using melamine as a precursor for the copolymerization process, g-C3N4 and g-C3N4/TCNQ/Eu complexes with various amounts of doping were created. These complexes were then examined using XRD, FT-IR, SEM, TEM, XPS, PL, UV-vis, and I-T. The degradation rates of pefloxacin (PEF), enrofloxacin (ENR), and ciprofloxacin (CIP) were 91.1%, 90.8%, and 93.2% under visible light (λ > 550 nm). The photocatalytic performance of the composite was analyzed, and the best effect was obtained for CIP photocatalysis when Eu doping was 3 mg at 20 °C and pH 7. Kinetic analysis showed that there was a linear relationship between the sample and the photocatalytic time, and the degradation rate was about 5 times that of g-C3N4. The cyclic stability of the g-C3N4/TCNQ/Eu composite sample was found to be good through repeated experiments. UPLC-MS visualizes the degradation process of CIP. The extremely low stability of piperazine ring induced subsequent degradation, followed by the fracture of quinolone ring promoting the complete decomposition of CIP.

Photocatalytic Self-Fenton System of g-C3N4-Based for Degradation of Emerging Contaminants: A Review of Advances and Prospects

The discharge of emerging pollutants in the industrial process poses a severe threat to the ecological environment and human health. Photocatalytic self-Fenton technology combines the advantages of photocatalysis and Fenton oxidation technology through the in situ generation of hydrogen peroxide (H2O2) and interaction with iron (Fe) ions to generate a large number of strong reactive oxygen species (ROS) to effectively degrade pollutants in the environment. Graphite carbon nitride (g-C3N4) is considered as the most potential photocatalytic oxygen reduction reaction (ORR) photocatalyst for H2O2 production due to its excellent chemical/thermal stability, unique electronic structure, easy manufacturing, and moderate band gap (2.70 eV). Hence, in this review, we briefly introduce the advantages of the photocatalytic self-Fenton and its degradation mechanisms. In addition, the modification strategy of the g-C3N4-based photocatalytic self-Fenton system and related applications in environmental remediation are fully discussed and summarized in detail. Finally, the prospects and challenges of the g-C3N4-based photocatalytic self-Fenton system are discussed. We believe that this review can promote the construction of novel and efficient photocatalytic self-Fenton systems as well as further application in environmental remediation and other research fields.

One-Pot Synthesis of N-Doped NiO for Enhanced Photocatalytic CO2 Reduction with Efficient Charge Transfer

The green and clean sunlight-driven catalytic conversion of CO₂ into high-value-added chemicals can simultaneously solve the greenhouse effect and energy problems. The controllable preparation of semiconductor catalyst materials and the study of refined structures are of great significance for the in-depth understanding of solar-energy-conversion technology. In this study, we prepared nitrogen-doped NiO semiconductors using a one-pot molten-salt method. The research shows that the molten-salt system made NiO change from p-type to n-type. In addition, nitrogen doping enhanced the adsorption of CO₂ on NiO and increased the separation of photogenerated carriers on the NiO. It synergistically optimized the CO₂-reduction system and achieved highly active and selective CO₂ photoreduction. The CO yield on the optimal nitrogen-doped photocatalyst was 235 μmol·g^-1·h^-1 (selectivity 98%), which was 16.8 times that of the p-type NiO and 2.4 times that of the n-type NiO. This can be attributed to the fact that the nitrogen doping enhanced the oxygen vacancies of the NiOs and their ability to adsorb and activate CO₂ molecules. Photoelectrochemical characterization also confirmed that the nitrogen-doped NiO had excellent electron -transfer and separation properties. This study provides a reference for improving NiO-based semiconductors for photocatalytic CO₂ reduction.

Advancing charge carriers separation and transformation by nitrogen self-doped hollow nanotubes g-C3N4 for enhancing photocatalytic degradation of organic pollutants

The rapid recombination of photogenerated electrons and holes, low utilization of visible light and weak oxidation capacity significantly limit the photocatalytic activity for the degradation of organic pollutants. Doping is used as a conventional strategy for regulating the electronic structure of photocatalysts to obtain a wider light absorption, but also suffers from the problems of reduced charge mobility and oxidation capacity, which is not conducive to photocatalytic degradation of pollutants. To address this issue, a nitrogen self-doped hollow nanotubes g-C₃N₄ (N-PCN) was synthesized by synergistic self-doping and quantum confinement effects. The N-PCN exhibits excellent efficiency in photocatalytic degradation of TC compared to the pristine g-C₃N₄. The synthesized N-PCN has a more positive conduction band minimum and can generate more photogenerated electrons to reduce oxygen to superoxide radicals. In addition, experimental and theoretical evidence shows that N-self-doping not only suppresses the recombination of photogenerated charge carriers but also facilitates the adsorption of oxygen molecules. Consequently, more superoxide radicals and singlet oxygen are generated through oxygen activation process.

Non-Metal-Doped Porous Carbon Nitride Nanostructures for Photocatalytic Green Hydrogen Production

Photocatalytic green hydrogen (H2) production through water electrolysis is deemed as green, efficient, and renewable fuel or energy carrier due to its great energy density and zero greenhouse emissions. However, developing efficient and low-cost noble-metal-free photocatalysts remains one of the daunting challenges in low-cost H2 production. Porous graphitic carbon nitride (gCN) nanostructures have drawn broad multidisciplinary attention as metal-free photocatalysts in the arena of H2 production and other environmental remediation. This is due to their impressive catalytic/photocatalytic properties (i.e., high surface area, narrow bandgap, and visible light absorption), unique physicochemical durability, tunable electronic properties, and feasibility to synthesize in high yield from inexpensive and earth-abundant resources. The physicochemical and photocatalytic properties of porous gCNs can be easily optimized via the integration of earth-abundant heteroatoms. Although there are various reviews on porous gCN-based photocatalysts for various applications, to the best of our knowledge, there are no reviews on heteroatom-doped porous gCN nanostructures for the photocatalytic H2 evolution reaction (HER). It is essential to provide timely updates in this research area to highlight the research related to fabrication of novel gCNs for large-scale applications and address the current barriers in this field. This review emphasizes a panorama of recent advances in the rational design of heteroatom (i.e., P, O, S, N, and B)-doped porous gCN nanostructures including mono, binary, and ternary dopants for photocatalytic HERs and their optimized parameters. This is in addition to H2 energy storage, non-metal configuration, HER fundamental, mechanism, and calculations. This review is expected to inspire a new research entryway to the fabrication of porous gCN-based photocatalysts with ameliorated activity and durability for practical H2 production.

Evaluation of a photoelectrochemical platform based on strontium titanate, sulfur doped carbon nitride and palladium nanoparticles for detection of SARS-CoV-2 spike glycoprotein S1

This work aims to develop a photoelectrochemical (PEC) platform for detection of SARS-CoV-2 spike glyprotein S1. The PEC platform is based on the modification of a fluorine-doped tin oxide (FTO) coated glass slide with strontium titanate (SrTiO₃ or ST), sulfur-doped carbon nitride (g-C₃N₄-S or CNS) and palladium nanoparticles entrapped in aluminum hydroxide matrix (PdAlO(OH) or PdNPs). The PEC platform was denoted as PdNPs/CNS/ST/FTO and it was characterized by SEM, TEM, FTIR, DRX, and EIS. The PEC response of the PdNPs/CNS/ST/FTO platform was optimized by evaluating the effects of the concentration of the donor molecule, the nature of the buffer, pH, antibody concentration, potential applied to the working electrode, and incubation time. The optimized PdNPs/CNS/ST/FTO PEC platform was modified with 5 μg mL^-1 of antibody for determination of SARS-CoV-2 spike glycoprotein S1. A decrease in the photocurrent was observed with an increase in the concentration of SARS-CoV-2 from 1 fg mL^-1 to 1000 pg mL^-1 showing that the platform is a promising alternative for the detection of S1 protein from SARS-CoV-2. The designed PEC platform exhibited recovery percentages of 96.20% and 109.65% in artificial saliva samples.

Olive Mill Wastewater Remediation: From Conventional Approaches to Photocatalytic Processes by Easily Recoverable Materials

Olive oil production in Mediterranean countries represents a crucial market, especially for Spain, Italy, and Greece. However, although this sector plays a significant role in the European economy, it also leads to dramatic environmental consequences. Waste generated from olive oil production processes can be divided into solid waste and olive mill wastewaters (OMWW). These latter are characterized by high levels of organic compounds (i.e., polyphenols) that have been efficiently removed because of their hazardous environmental effects. Over the years, in this regard, several strategies have been primarily investigated, but all of them are characterized by advantages and weaknesses, which need to be overcome. Moreover, in recent years, each country has developed national legislation to regulate this type of waste, in line with the EU legislation. In this scenario, the present review provides an insight into the different methods used for treating olive mill wastewaters paying particular attention to the recent advances related to the development of more efficient photocatalytic approaches. In this regard, the most advanced photocatalysts should also be easily recoverable and considered valid alternatives to the currently used conventional systems. In this context, the optimization of innovative systems is today’s object of hard work by the research community due to the profound potential they can offer in real applications. This review provides an overview of OMWW treatment methods, highlighting advantages and disadvantages and discussing the still unresolved critical issues.

Preparation of Cu modified g-C3N4 nanorod bundles for efficiently photocatalytic CO2 reduction

Carbon nitride-based photocatalysts for CO₂ reduction have received great attention. The introduction of transition metals can effectively improve the photocatalytic efficiency of carbon nitride. However, how to introduce transition metals into carbon nitride in more ways remains a challenge. Herein, the Cu modified g-C₃N₄ nanorod bundles (CCNBs) were prepared by chemical vapor co-deposition using the mixture of urea and chlorophyllin sodium copper salt as precursor. The prepared CCNBs exhibited excellent photocatalytic activity for CO₂ reduction. The unique hierarchical structure was beneficial to enhance light harvesting. Besides, the introduction of uniformly dispersed Cu further improved the absorption capacity of visible light, increased active sites, and promoted the separation and transfer of carriers. The CO yield of CCNBs was 5 times higher than that of bulk g-C₃N₄, and showed excellent stability in cycle experiments. This work provides a strategy to prepare carbon nitride-based photocatalysts for efficient CO₂ reduction.

Recent Advances in g-C3 N4 -Based Photocatalysts for Pollutant Degradation and Bacterial Disinfection: Design Strategies, Mechanisms, and Applications

Emerging photocatalytic technology promises to provide an effective solution to the global energy crisis and environmental pollution. Graphite carbon nitride (g-C₃ N₄ ) has gained extensive attention in the scientific community due to its excellent physical and chemical properties, attractive electronic band structure, and low cost. In this paper, research progress in design strategies for g-C₃ N₄ -based photocatalysts in the past five years is reviewed from the perspectives of nanostructure construction, element doping, and heterostructure construction. To clarify the relationship between application requirements and structural design, variations in the morphology, electronic energy band structure, light absorption capacity, as well as interfacial charge transfer caused by various modification strategies are discussed in detail. The recent applications of g-C₃ N₄ -based photocatalysts for pollutant degradation and bacterial disinfection are reviewed, as well as the antimicrobial activity and degradation mechanisms. Finally, current challenges and future development directions for the practical application of g-C₃ N₄ -based photocatalysts are tentatively discussed.

Exfoliation-induced O-doped g-C3N4 Nanosheets with improved photoreactivity towards RhB degradation and H2 evolution

Graphitic carbon nitride (g-C3N4) nanosheets exfoliated from bulk-sized counterparts are limited by quantum size effect-induced widened bandgap. In this work, a (NH4)2S2O8 (APS) induced thermal exfoliation approach is introduced to...

Enhanced visible-light-driven RhB removal with a Mo–Ni bimetallic sulfide/g-C3N4 nanosheet Schottky junction

A novel Schottky heterojunction is fabricated from narrow bandgap Mo–Ni bimetallic sulfide and g-C3N4 nanosheets to maximize carrier separation.

Interface modification by defect engineering for g-C3N4/LaPO4−x nanorods towards efficient CO2 photoreduction

In this work, a series of specific surface defects are introduced at the interface of LaPO4/g-C3N4 composites.

Photocatalytic Z-Scheme Overall Water Splitting: Recent Advances in Theory and Experiments

Photocatalytic water splitting is considered one of the most important and appealing approaches for the production of green H₂ to address the global energy demand. The utmost possible form of artificial photosynthesis is a two-step photoexcitation known as "Z-scheme", which mimics the natural photosystem. This process solely relies on the effective coupling and suitable band positions of semiconductors (SCs) and redox mediators for the purpose to catalyze the surface chemical reactions and significantly deter the backward reaction. In recent years, the Z-scheme strategies and their key role have been studied progressively through experimental approaches. In addition, theoretical studies based on density functional theory have provided detailed insight into the mechanistic aspects of some breathtakingly complex problems associated with hydrogen evolution reaction and oxygen evolution reaction. In this context, this critical review gives an overview of the fundamentals of Z-scheme photocatalysis, including both theoretical and experimental advancements in the field of photocatalytic water splitting, and suggests future perspectives.

Formation of unique hollow ZnSnO3@ZnIn2S4 core-shell heterojunction to boost visible-light-driven photocatalytic water splitting for hydrogen production

Herein, it is reported that a batch of hollow core-shell heterostructure photocatalysts were carefully fabricated using a reliable and convenient low-temperature solvothermal method, and ultra-thin ZnIn₂S₄ nanosheets are grown in situ on the hollow ZnSnO₃ cubes to achieve efficient photocatalytic hydrogen evolution. This unique layered hollow structure utilizes multiple light scattering/reflection within the cavity to enhance light absorption, the thin shell reduces the path of charge transfer, and the irregular nanosheets-wrapped outer layer not only enhances the adsorption power, but also provides an abundant active sites to promote the efficiency of photocatalytic water splitting to produce hydrogen. Therefore, due to the matching energy band and unique structure, the ZnSnO₃@ZnIn₂S₄ hollow core-shell heterostructure photocatalyst exhibits superior H₂ production efficiency (16340.18 μmol h^-1 g^-1) and outstanding stability. This work emphasizes the importance of carefully designing a suitable material structure in addition to adjusting the chemical composition.

Well-designed three-dimensional hierarchical hollow tubular g-C3N4/ZnIn2S4 nanosheets heterostructure for achieving efficient visible-light photocatalytic hydrogen evolution

Photocatalytic water splitting for hydrogen production is an important strategy to achieve clean energy development. In this report, a novel three-dimensional (3D) hierarchical hollow tubular g-C₃N₄/ZnIn₂S₄ nanosheets (HTCN/ZIS) type-Ⅱ heterojunction photocatalyst was successfully prepared and applied for photocatalytic hydrogen production under visible light irradiation. The experimental results reveal that the optimal proportion of HTCN/ZIS with the remarkable photocatalytic H₂ evolution rate of 20738 μmol h^-1 g^-1 was obtained. The main reasons for the improvement of hydrogen production activity are as follows: (i) this unique tubular hollow structure can effectively enhances the light capturing ability by the multiple light scattering/reflection of incident light in the inner cavity; (ii) the shorten the phase plane transmission distance could reduce the path of charge transfer; (iii) the surface coated a large number of scaly ZnIn₂S₄ nanosheets can provide abundant reactive sites. Combining the various characterization tests, the enhanced spatial segregation of charge carriers could owning to the intimately interfacial contact and well-matched band gaps structure between g-C₃N₄ and ZnIn₂S₄ through the type-II heterojunction. This work provides a new prospect for the construction of a novel 3D hierarchical type-II heterojunction photocatalyst for highly efficient photocatalytic hydrogen production.

Synergistic adsorption-photocatalytic degradation of different antibiotics in seawater by a porous g-C3N4/calcined-LDH and its application in synthetic mariculture wastewater

In this work, a modified g-C₃N₄/MgZnAl-calcined layered double hydroxide composite (M-CN/cLDH) was successfully fabricated via a template method. The composite material is a hierarchical porous flower-like nanostructure self-assembled from stacked hybrid flakes. The 3D M-CN/cLDH architectures exhibit a synergistic effect of adsorption and photocatalysis for eliminating typical tetracycline antibiotics in seawater, i.e., oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), and doxycycline (DXC). The synergistic removal rate of OTC in seawater of M-CN/cLDH is 2.73 times higher than that of g-C₃N₄ after 120 min of visible-light illumination, and M-CN/cLDH also performs better adsorption-photocatalytic degradation on OTC in the continuous flow reaction process. The superior adsorption capability of the M-CN/cLDH is attributed to the open porous structures of cLDH, and its excellent photocatalytic degradation activity is ascribed to the closely bonded heterojunctions between g-C₃N₄ (CN) and cLDH double layers. The mass spectra reveals the degradation pathways of OTC, and its byproducts are less toxic after degradation for 120 min. The exploration of the M-CN/cLDH in synthetic mariculture wastewater suggested a huge potential for its practical application. With the assistance of magnesium ammonium phosphate (MAP) precipitation pretreatment, the material can effectively retain the high OTC removal rate in the synthetic mariculture wastewater circumstance.

Urea-induced supramolecular self-assembly strategy to synthesize wrinkled porous carbon nitride nanosheets for highly-efficient visible-light photocatalytic degradation

Graphitic carbon nitride (g-C3N4) has attracted immense interest as a promising photocatalyst. To facilitate its versatile applications in many fields, new low-cost strategies to synthesize outstanding g-C3N4 need to be further developed. Although supramolecular preorganization has been considered as a promising candidate, the utilized supramolecules like melamine-cyanuric acid (MCA) are typically synthesized by expensive triazine derivatives. Herein, wrinkled porous g-C3N4 nanosheets were successfully fabricated by hydrothermal-annealing of supramolecular intermediate MCA synthesized by the cheap precursors dicyandiamide and urea. During the formation of MCA, urea could act as a facile agent to react with dicyandiamide to form melamine and cyanuric acid firstly and then assemble into MCA through hydrogen bonds. In addition, urea could serve as a porogen and decompose to generate bubbles for conducive formation of micro-size MCA self-templates and thus wrinkled porous g-C3N4 nanosheets could be obtained. The nanostructure and photocatalytic performance of g-C3N4 were optimized by modulating microstructures and physicochemical properties of MCA, which could be conveniently controlled by urea addition and hydrothermal duration. The obtained wrinkled porous g-C3N4 nanosheets exhibit highly-efficient visible-light photocatalytic degradation compared with traditional MCA-derived g-C3N4, which could remove 98.3% of the rhodamine B in 25 min. The superior photocatalytic activity is mainly attributed to the urea-induced larger specific surface area, better light harvesting ability, faster transfer and more advanced separation efficiency of the photogenerated electron-hole pairs. This research provides a new strategy for preparing high-performance porous g-C3N4 from the self-assembled supramolecule MCA synthesized by low-cost precursors.

Catalytic conversion of seawater to fuels: Eliminating N vacancies in g-C3N4 to promote photocatalytic hydrogen production

The use of solar energy to decompose seawater and produce hydrogen is of great significance in solving the energy crisis. Numerous studies have shown that vacancies can significantly improve photocatalytic activity due to their electron-rich nature. However, our recent research has shown that materials with vacancies are not suitable for photocatalytic reactions in seawater. In this study, g-C₃N₄ with rich N vacancies was selected as the research object, and urea was used as the precursor; in this system, the N vacancies in g-C₃N₄ could be effectively reduced by the addition of ZIF-8 (ZCNQx). The activity of ZCNQ40 was 5.6 times higher than that of g-C₃N₄ in fresh seawater, but only 3.1 times higher in freshwater. Based on the analysis of the experimental results, we believe that g-C₃N₄ has a limiting relationship between H+ adsorption catalysis and H₂ product desorption. In addition, seawater contains many heteroatoms that will also compete with proton (H+) reduction. The results of our study show that catalysts with vacancies are not necessarily suitable for catalytic reactions in seawater media. This research will stimulate new ideas for research into the conversion of solar energy to chemical energy in seawater media.

The CdS/g-C3N4 nano-photocatalyst: Brief characterization and kinetic study of photodegradation and mineralization of methyl orange

The CdS/g-C₃N₄ hybrid was prepared mechanically and characterized by different techniques including XRD, SEM, DRS, FTIR, and cyclic voltammetry (CV). The SEM study showed that CdS nanoparticles (NPs) have been randomly dispersed on the surface of graphitic carbon nitride (g-C₃N₄). The CV results showed better charge carriers' transfer for the modified carbon paste electrode (CPE) by the CdS/g-C₃N₄ system concerning the modified CPE by single CdS or g-C₃N₄ modifier. The band gap (Bg) energies of 1.7, 2.7, and 1.9 eV were obtained from DRS results for CdS, g-C₃N₄, and CdS/g-C₃N₄ systems, respectively. The photocatalytic activity of the single and hybrid systems was tested towards methyl orange (MO). The degradation extents of 16%, 22%, and 34% were respectively obtained for CdS NPs, g-C₃N₄, and CdS/g-C₃N₄ systems at initial steps. To enhance the degradation efficiency, the mole ratio of the component was changed in the second step. The work was then focused on the kinetic study of both photodegradation and mineralization processes. For this goal, the degradation extents of the photodegraded MO solutions were calculated based on the recorded absorbance of the solutions in the visible-light and the results were then subjected to the Hinshelwood equation. Then the solutions were subjected to COD experiment to follow the mineralization extent of MO. Form the slopes of the Hinshelwood plots, the rate constants of 0.024 and 0.025 min^-1 were obtained for the degradation and mineralization of MO molecules, respectively. TOC results confirmed the mineralization of 187.5 μmoles of MO molecules in a 50 ppm MO solution.

Highly enhanced H2 evolution of MoO3/g-C3N4 hybrid composites based on a direct Z-scheme photocatalytic system

A direct Z-scheme MoO₃/g-C₃N₄ heterojunction with appropriate oxygen vacancies is successfully fabricated via an in situ method of a one-pot pyrolysis strategy.

Facile Synthesis of Defect-Modified Thin-Layered and Porous g-C3N4 with Synergetic Improvement for Photocatalytic H2 Production

Modulating and optimizing the diverse parameters of photocatalysts synergistically as well as exerting these advantages fully in photocatalytic reactions are crucial for the sufficient utilization of solar energy but still face various challenges. Herein, a novel and facile urea- and KOH-assisted thermal polymerization (UKATP) strategy is first developed for the preparation of defect-modified thin-layered and porous g-C₃N₄ (DTLP-CN), wherein the thickness of g-C₃N₄ was dramatically decreased, and cyano groups, nitrogen vacancies, and mesopores were simultaneously introduced into g-C₃N₄. Importantly, the roles of thickness, pores, and defects can be targetedly modulated and optimized by changing the mass ratio of urea, KOH, and melamine. This can remarkably increase the specific area, improve the light-harvesting capability, and enhance separation efficiency of photoexcited charge carriers, strengthening the mass transfer in g-C₃N₄. Consequently, the photocatalytic hydrogen evolution efficiency of the DTLP-CN (1.557 mmol h^-1 g^-1, λ > 420 nm) was significantly improved more than 48.5 times with the highest average apparent quantum yield (AQY) of 18.5% and reached as high as 0.82% at 500 nm. This work provides an effective strategy for synergistically regulating the properties of g-C₃N₄, and opens a new horizon to design g-C₃N₄-based catalysts for highly efficient solar-energy conversion.

Doping of Graphitic Carbon Nitride with Non-Metal Elements and Its Applications in Photocatalysis

This review outlines the latest research into the design of graphitic carbon nitride (g-C3N4) with non-metal elements. The emphasis is put on modulation of composition and morphology of g-C3N4 doped with oxygen, sulfur, phosphor, nitrogen, carbon as well as nitrogen and carbon vacancies. Typically, the various methods of non-metal elements introducing in g-C3N4 have been explored to simultaneously tune the textural and electronic properties of g-C3N4 for improving its response to the entire visible light range, facilitating a charge separation, and prolonging a charge carrier lifetime. The application fields of such doped graphitic carbon nitride are summarized into three categories: CO2 reduction, H2-evolution, and organic contaminants degradation. This review shows some main directions and affords to design the g-C3N4 doping with non-metal elements for real photocatalytic applications.

Oxygen-defective ZnO porous nanosheets modified by carbon dots to improve their visible-light photocatalytic activity and gain mechanistic insight

A carbon dots/oxygen-defective ZnO (COZ) porous nanosheet composite photocatalyst was prepared via a one-step liquid-phase wet chemistry method for the highly efficient visible-light photocatalytic degradation of tetracycline (TC).