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.

Exploring cheap and efficient cocatalysts for enhancing the performance of photocatalysts is a challenge in the energy conversion field. Herein, 2D ultrathin Ti3C2 nanosheets, a kind of MXenes, are prepared by etching Ti3AlC2 with subsequent ultrasonic exfoliation. A novel 2D/2D heterojunction of ultrathin Ti3C2/Bi2WO6 nanosheets is then successfully prepared by in situ growth of Bi2WO6 ultrathin nanosheets on the surface of these Ti3C2 ultrathin nanosheets. The resultant Ti3C2/Bi2WO6 hybrids exhibit a short charge transport distance and a large interface contact area, assuring excellent bulk‐to‐surface and interfacial charge transfer abilities. Meanwhile, the improved specific surface area and pore structure endow Ti3C2/Bi2WO6 hybrids with an enhanced CO2 adsorption capability. As a result, the 2D/2D heterojunction of ultrathin Ti3C2/Bi2WO6 nanosheets shows significant improvement on the performance of photocatalytic CO2 reduction under simulated solar irradiation. The total yield of CH4 and CH3OH obtained on the optimized Ti3C2/Bi2WO6 hybrid is 4.6 times that obtained on pristine Bi2WO6 ultrathin nanosheets. This work provides a new protocol for constructing 2D/2D photocatalytic systems and demonstrates Ti3C2 as a promising and cheap cocatalyst.

Graphitic carbon nitride (g-C3N4)-based photocatalysts have attracted dramatically increasing interest in the area of visible-light-induced photocatalytic hydrogen generation due to the unique electronic band structure and high thermal and chemical stability of g-C3N4. This Perspective summarizes the recent significant advances on designing high-performance g-C3N4-based photocatalysts for hydrogen generation under visible-light irradiation. The rational strategies such as nanostructure design, band gap engineering, dye sensitization, and heterojunction construction are described. Finally, this Perspective highlights the ongoing challenges and opportunities for the future development of g-C3N4-based photocatalysts in the exciting research area.

Heterogeneous catalysis is one of the most important chemical processes of various industries performed on catalyst nanoparticles with different sizes or/and shapes. In the past two decades, the catalytic performances of different catalytic reactions on nanoparticles of metals and oxides with well controlled sizes or shapes have been extensively studied thanks to the spectacular advances in syntheses of nanomaterials of metals and oxides. This review discussed the size and shape effects of catalyst particles on catalytic activity and selectivity of reactions performed at solid-gas or solid-liquid interfaces with a purpose of establishing correlations of size- and shape-dependent chemical and structural factors of surface of a catalyst with the corresponding catalytic performances toward understanding of catalysis at a molecular level.

Constructing heterojunctions between two semiconductors with matched band structure is an effective strategy to acquire high‐efficiency photocatalysts. The S‐scheme heterojunction system has shown great potential in facilitating separation and transfer of photogenerated carriers, as well as acquiring strong photoredox ability. Herein, a 0D/2D S‐Scheme heterojunction material involving CeO2 quantum dots and polymeric carbon nitride (CeO2/PCN) is designed and constructed by in situ wet chemistry with subsequent heat treatment. This S‐scheme heterojunction material shows high‐efficiency photocatalytic sterilization rate (88.1 %) towards Staphylococcus aureus (S. aureus) under visible‐light irradiation (λ≥420 nm), which is 2.7 and 8.2 times that of pure CeO2 (32.2 %) and PCN (10.7 %), respectively. Strong evidence of S‐scheme charge transfer path is verified by theoretical calculations, in situ irradiated X‐ray photoelectron spectroscopy, and electron paramagnetic resonance.

Two-dimensional (2D) layered nanostructure composites are promising candidates for conducting high-performance energy conversion and environmental remediation. The construction of 2D layered composite photocatalysts can generate many unique properties that do not exist in other kinds of semiconductor composite photocatalyst, which are beneficial for photocatalytic performance enhancement, band gap tuning, heterojunction formation, etc. Recently, these advantages have greatly stimulated the study of 2D layered composite photocatalysts in the field of photocatalysis. This feature article summarizes the recent developments of 2D layered composite photocatalysts for photocatalytic applications, such as photocatalytic hydrogen production, bacterial disinfection, and pollutant degradation. Finally, perspectives on the challenges and opportunities for the future exploration of 2D layered composite photocatalysts are put forward.

This work demonstrates the development of hierarchical ultra-thin g-C3N4 nanosheets with enhanced photocatalytic CO2 reduction activity.

Inspired by natural photosynthesis, constructing inorganic/organic heterojunctions is regarded as an effective strategy to design high‐efficiency photocatalysts. Herein, a step (S)‐scheme heterojunction photocatalyst is prepared by in situ growth of an inorganic semiconductor firmly on an organic semiconductor. A new pyrene‐based conjugated polymer, pyrene‐alt‐triphenylamine (PT), is synthesized via the typical Suzuki–Miyaura reactions, and then employed as a substrate to anchor CdS nanocrystals. The optimized CdS/PT composite, coupling 2 wt% PT with CdS, exhibits a robust H2 evolution rate of 9.28 mmol h−1 g−1 with continuous release of H2 bubbles, as well as a high apparent quantum efficiency of 24.3%, which is ≈8 times that of pure CdS. The S‐scheme charge transfer mechanism between PT and CdS, is systematically demonstrated by photoirradiated Kelvin probe measurement and in situ irradiated X‐ray photoelectron spectroscopy analyses. This work provides a protocol for preparing specific S‐scheme heterojunction photocatalysts on the basis of inorganic/organic coupling.