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-based photocatalysis is considered to be an attractive way for solving the worldwide energy shortage and environmental pollution issues. Since the pioneering work in 2009 on graphitic carbon nitride (g-C3N4) for visible-light photocatalytic water splitting, g-C3N4 -based photocatalysis has become a very hot research topic. This review summarizes the recent progress regarding the design and preparation of g-C3N4 -based photocatalysts, including the fabrication and nanostructure design of pristine g-C3N4 , bandgap engineering through atomic-level doping and molecular-level modification, and the preparation of g-C3N4 -based semiconductor composites. Also, the photo-catalytic applications of g-C3N4 -based photocatalysts in the fields of water splitting, CO2 reduction, pollutant degradation, organic syntheses, and bacterial disinfection are reviewed, with emphasis on photocatalysis promoted by carbon materials, non-noble-metal cocatalysts, and Z-scheme heterojunctions. Finally, the concluding remarks are presented and some perspectives regarding the future development of g-C3N4 -based photocatalysts are highlighted.

Polymeric Photocatalysts Based on Graphitic Carbon Nitride

A review on g-C3N4-based photocatalysts

Photocatalysis is considered as one of the promising routes to solve the energy and environmental crises by utilizing solar energy. Graphitic carbon nitride (g-C3N4) has attracted worldwide attention due to its visible-light activity, facile synthesis from low-cost materials, chemical stability, and unique layered structure. However, the pure g-C3N4 photocatalyst still suffers from its low separation efficiency of photogenerated charge carriers, which results in unsatisfactory photocatalytic activity. Recently, g-C3N4-based heterostructures have become research hotspots for their greatly enhanced charge carrier separation efficiency and photocatalytic performance. According to the different transfer mechanisms of photogenerated charge carriers between g-C3N4 and the coupled components, the g-C3N4-based heterostructured photocatalysts can be divided into the following categories: g-C3N4-based conventional type II heterojunction, g-C3N4-based Z-scheme heterojunction, g-C3N4-based p–n heterojunction, g-C3N4/metal heterostructure, and g-C3N4/carbon heterostructure. This review summarizes the recent significant progress on the design of g-C3N4-based heterostructured photocatalysts and their special separation/transfer mechanisms of photogenerated charge carriers. Moreover, their applications in environmental and energy fields, e.g., water splitting, carbon dioxide reduction, and degradation of pollutants, are also reviewed. Finally, some concluding remarks and perspectives on the challenges and opportunities for exploring advanced g-C3N4-based heterostructured photocatalysts are presented.

g-C3N4-Based Heterostructured Photocatalysts

S-Scheme Heterojunction Photocatalyst

Noble-metal-free Ni2P as cocatalyst decorated rapid microwave solvothermal synthesis of inorganic-organic CdS-DETA hybrids for enhanced photocatalytic hydrogen evolution

In-situ fabrication of Bi2S3/BiVO4/Mn0.5Cd0.5S-DETA ternary S-scheme heterostructure with effective interface charge separation and CO2 reduction performance

Recently, cadmium selenide (CdSe) has been deeply studied because of its excellent photocatalytic hydrogen (H2) production performance. However, pure CdSe has poor stability and severe photocorrosion, which seriously affect its application prospect. In this work, we successfully deposit Bi2MoO6 on an inorganic-organic CdSe-diethylenetriamine (DETA) hybrid to design Bi2MoO6/CdSe-DETA composites by an in situ solvothermal method. The morphology, crystal structure, electrochemical properties, H2 evolution performance and the photostability of Bi2MoO6/CdSe-DETA composites are explored using various techniques. The results show that the as-prepared Bi2MoO6/CdSe-DETA composites exhibit excellent photocatalytic performance and photostability under visible light irradiation. Among them, the Bi2MoO6/CdSe-DETA hybrid system exhibits excellent photocatalytic H2 production performance (5.92 mmol g-1 h-1), which is approximately 3.6 and 1.8 times higher than that of pure CdSe and CdSe-DETA, respectively. After 4 cycles, the photocatalyst still maintains high H2 production. This study develops a new type of photocatalyst that can respond to visible light. This provides an effective way to solve the energy problem by using solar energy.

Jinfeng Zhang

Papers

Noble-metal-free Ni2P as cocatalyst decorated rapid microwave solvothermal synthesis of inorganic-organic CdS-DETA hybrids for enhanced photocatalytic hydrogen evolution

In-situ fabrication of Bi2S3/BiVO4/Mn0.5Cd0.5S-DETA ternary S-scheme heterostructure with effective interface charge separation and CO2 reduction performance

A Z-scheme Bi2MoO6/CdSe-diethylenetriamine heterojunction for enhancing photocatalytic hydrogen production activity under visible light

Branch-like Cd Zn1-Se/Cu2O@Cu step-scheme heterojunction for CO2 photoreduction

Plasmonic Bi-enhanced ammoniated α-MnS/Bi2MoO6 S-scheme heterostructure for visible-light-driven CO2 reduction