As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Semiconductor polymeric graphitic carbon nitride (g-C3N4) photocatalysts have attracted dramatically growing attention in the field of the visible-light-induced hydrogen evolution reaction (HER) because of their facile synthesis, easy functionalization, attractive electronic band structure, high physicochemical stability and photocatalytic activity. This review article presents a panorama of the latest advancements in the rational design and development of g-C3N4 and g-C3N4-based composite photocatalysts for HER application. Concretely, the review starts with the development history, synthetic strategy, electronic structure and physicochemical characteristics of g-C3N4 materials, followed by the rational design and engineering of various nanostructured g-C3N4 (e.g. thinner, highly crystalline, doped, and porous g-C3N4) photocatalysts for HER application. Then a series of highly efficient g-C3N4 (e.g., metal/g-C3N4, semiconductor/g-C3N4, metal organic framework/g-C3N4, carbon/g-C3N4, conducting polymer/g-C3N4, sensitizer/g-C3N4) composite photocatalysts are exemplified. Lastly, this review provides a comprehensive summary and outlook on the major challenges, opportunities, and inspiring perspectives for future research in this hot area on the basis of pioneering works. It is believed that the emerging g-C3N4-based photocatalysts will act as the “holy grail” for highly efficient photocatalytic HER under visible-light irradiation.

Semiconductor polymeric graphitic carbon nitride photocatalysts: the “holy grail” for the photocatalytic hydrogen evolution reaction under visible light

The design and synthesis of robust and efficient photocatalysts for water splitting to generate hydrogen is deemed to be a promising approach for sustainable energy sources. In this work, noble-metal-free nanostructured ternary NiS/CDs/CdS (NCCS) photocatalysts were elaborately designed and successfully synthesized for high-efficient hydrogen evolution. Taking the advantages of strong absorption and electron buffer property of carbon dots (CDs), as well as merits of internal p-n junction formed between NiS and CdS, the as-prepared NCCS composite shows prominent promotion of hydrogen evolution in comparison with single CdS photocatalyst and binary hybrids (NiS/CdS and CDs/CdS). Remarkably, the optimal ternary hybrid achieves a hydrogen production rate as high as 1444.5 μmol h−1 g−1 under visible light irradiation (λ > 420 nm), up to 5.38 times over bare CdS spheres. This work paves a new pathway for the rational design of efficient hybrid photocatalysts toward solar energy conversion to chemical fuels.

Dual-cocatalysts decorated rimous CdS spheres advancing highly-efficient visible-light photocatalytic hydrogen production

Peroxymonosulfate activation for efficient sulfamethoxazole degradation by Fe3O4/β-FeOOH nanocomposites: Coexistence of radical and non-radical reactions

Bacterial infection and associated complications are threats to human health especially when biofilms form on biomedical devices and artificial implants. Herein, a hybrid polydopamine (PDA)/Ag3PO4/graphene oxide (GO) coating is designed and constructed to achieve rapid bacteria killing and eliminate biofilms in situ. By varying the amount of GO in the hybrid coating, the bandgap can be tuned from 2.52 to 2.0 eV so that irradiation with 660 nm visible light produces bacteria-killing effects synergistically in concert with reactive oxygen species (ROS). GO regulates the release rate of Ag+ to minimize the cytotoxicity while maintaining high antimicrobial activity, and a smaller particle size enhances the yield of ROS. After irradiation with 660 nm visible light for 15 min, the antimicrobial rates of the PDA/Ag3PO4/GO hybrid coating against Escherichia coli and Staphylococcus aureus are 99.53% and 99.66%, respectively. In addition, this hybrid coating can maintain a repeatable and sustained antibacterial eff...

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Tuning the Bandgap of Photo-Sensitive Polydopamine/Ag3PO4/Graphene Oxide Coating for Rapid, Noninvasive Disinfection of Implants.

Seeking a simple and moderate route to generate reactive oxygen species (ROS) for antibiosis is of great interest and challenge. This work demonstrates that molecule transition and electron rearrangement processes can directly occur only through chemisorption interaction between the adsorbed O2 and high-energy {111} facet-exposed MgO with abundant surface oxygen vacancies (SOVs), hence producing singlet oxygen and superoxide anion radicals without light irradiation. These ROS were confirmed by electron paramagnetic resonance, in situ Raman, and scavenger experiments. Furthermore, heat plays a crucial role for the electron transfer process to accelerate the formation of ·O2–, which is verified by temperature kinetic experiments of nitro blue tetrazolium reduction in the dark. Therefore, the presence of oxygen vacancy can be considered as an intensification of the activation process. The designed MgO is acquired in one step via constructing a reduction atmosphere during the combustion reaction process, whic...

Synthesis of {111} Facet-Exposed MgO with Surface Oxygen Vacancies for Reactive Oxygen Species Generation in the Dark

The mismatches of lattices and energy bands in heterojunction are the dominant factors restricting the generation efficiency of reactive oxygen species (ROS) that are powerful tools for water purification and anti-bacteria. In this paper, the mediated lattice matching role of amorphous Al 2 O 3 is presented for constructing the ternary g-C 3 N 4 /Al 2 O 3 /ZnO heterojunctions, which exhibit higher molecular oxygen activation performance than binary g-C 3 N 4 /ZnO and g-C 3 N 4 /Al 2 O 3 heterojunctions. The oxygen activation ability and the ROS generation were testified by the electron paramagnetic resonance (EPR) measurement, transformation of nitroblue tetrazolium (NBT) and degradation of methylene blue (MB). The ROS include superoxide anion radical ( O 2 − ) and consequent product of hydroxyl radical ( OH). The superior oxygen activation performance of the ternary heterojunctions can be attributed to the lattices matching of the mediated amorphous Al 2 O 3 and the resultant efficient cascade electron transfer.

Fabrication of ternary g-C3N4/Al2O3/ZnO heterojunctions based on cascade electron transfer toward molecular oxygen activation

Heterojunctions of g-C3 N4 /Al2 O3 (g-C3 N4 =graphitic carbon nitride) are constructed by an in situ one-pot hydrothermal route based on the development of photoactive γ-Al2 O3 semiconductor with a mesoporous structure and a high surface area (188 m(2) g(-1) ) acting as electron acceptor. A structure modification function of g-C3 N4 for Al2 O3 in the hydrothermal process is found, which can be attributed to the coordination between unoccupied orbitals of the Al ions and lone-pair electrons of the N atoms. The as-synthesized heterojunctions exhibit much higher photocatalytic activity than pure g-C3 N4 . The hydrogen generation rate and the reaction rate constant for the degradation of methyl orange over 50 % g-C3 N4 /Al2 O3 under visible-light irradiation (λ>420 nm) are 2.5 and 7.3 times, respectively, higher than those over pristine g-C3 N4 . The enhanced activity of the heterojunctions is attributed to their large specific surface areas, their close contact, and the high interfacial areas between the components as well as their excellent adsorption performance, and efficient charge transfer ability.

Structure Modification Function of g‐C3N4 for Al2O3 in the In Situ Hydrothermal Process for Enhanced Photocatalytic Activity

Tuning Electronic Structure via CoS Clusters for Visual Photocatalytic H2 Production and Mechanism Insight

The invention discloses a g-C3N4/Al2O3/ZnO ternary heterojunction material with visible light catalytic activity and a preparation method thereof. The g-C3N4/Al2O3/ZnO ternary heterojunction material comprises, by weight 50-70% of g-C3N4, 45-20% of Al2O3 and 5-20% of ZnO. The preparation method of the g-C3N4/Al2O3/ZnO ternary heterojunction material comprises: dissolving suitable aluminum nitrate in distilled water, adding prepared g-C3N4 powder, stirring well, dropwise adding NaOH solution until pH is 8-9, stirring, dissolving in zinc nitrate, dropwise adding NaOH solution to maintain pH to 8-9, continuing to stir, filtering by suction, drying, and grinding to obtain a sample precursor, and calcining at 400 DEG C to obtain the g-C3N4/Al2O3/ZnO ternary heterojunction material. The preparation method is simple, the raw materials are low in rice, complex equipment is not required, the process is free of pollution, and the material is suitable for industrial batch production.

Shao-jia Liu

Papers

Synthesis of {111} Facet-Exposed MgO with Surface Oxygen Vacancies for Reactive Oxygen Species Generation in the Dark

Fabrication of ternary g-C3N4/Al2O3/ZnO heterojunctions based on cascade electron transfer toward molecular oxygen activation

Structure Modification Function of g‐C3N4 for Al2O3 in the In Situ Hydrothermal Process for Enhanced Photocatalytic Activity

Tuning Electronic Structure via CoS Clusters for Visual Photocatalytic H2 Production and Mechanism Insight

G-C3N4/Al2O3/ZnO Heterojunction with visible light catalytic activity and preparation method thereof