Graphitic carbon nitride (g-C3N4)-based photocatalytic materials for hydrogen evolution

Supermolecule Polymer Derived Porous Carbon Nitride Microspheres with Controllable Energy Band Structure for Photocatalytic Hydrogen Evolution Reaction

Porous graphitic carbon nitride microsphere with large specific surface area and controllable energy band structure is synthesized via a simple method with the supermolecule polymer of melamine-cyanuric acid (MCA) as the intermediates. The energy band structure and morphology of carbon nitride are closely correlative to the calcination time. And the CN-20 catalyst fabricated by calcination for 20 h exhibit superior photocatalytic activity of hydrogen evolution reaction (HER) under visible-light (λ ≥ 420 nm) irradiation. The photocatalytic and photoelectrochemical test results indicate that Pt is the optimum cocatalyst candidate compared with Pd, Ru, and Ag. Meanwhile, the time-dependent process of the intermediate pyrolysis to carbon nitride and the internal mechanism of photogenerated charge transfer between semiconductors and cocatalyst is investigated and supplemented by theoretical calculations. This work provides a novel and energy band structure controllable manufacture strategy for porous carbon nitride semiconductor with satisfying visible-light photocatalytic reduction performance.

Recent advances in ternary Z-scheme photocatalysis on graphitic carbon nitride based photocatalysts

Due to its excellent photocatalytic performance over the last few years, graphitic-like carbon nitride (g-C3N4) has garnered considerable notice as a photocatalyst. Nevertheless, several limitations, including small surface area, the rates at which photo-generated electrons and holes recombine are swift, and the inefficient separation and transport of photoexcited carriers continue to impede its solar energy utilization. To overcome those limitations in single-component g-C3N4, constructing a heterogeneous photocatalytic system has emerged as an effective way. Among the various studies involving the incorporation of hetero composite materials to design heterojunctions, among the most promising approaches is to assemble a Z-scheme photocatalytic configuration. The Z-scheme configuration is essential because it facilitates efficient photocarrier separation and exhibits superior redox ability in separated electrons and holes. Moreover, ternary composites have demonstrated enhanced photocatalytic activities and reinforced photostability. Ternary Z-scheme heterostructures constructed with g-C3N4 possess all the above-mentioned merits and provide a pioneering strategy for implementing photocatalytic systems for environmental and energy sustainability. A summary of the latest technological advancements toward design and fabrication in ternary all-solid-state Z-scheme (ASSZ) and direct Z-scheme (DZ) photocatalysts built on g-C3N4 is presented in this review. Furthermore, the review also discusses the application of ternary Z-scheme photocatalytic architecture established on g-C3N4.

Highly Efficient Solar-Light-Active Ag-Decorated g-C3N4 Composite Photocatalysts for the Degradation of Methyl Orange Dye

In this study, we utilized calcination and simple impregnation methods to successfully fabricate bare g-C₃N₄ (GCN) and x% Ag/g-C₃N₄ (x% AgGCN) composite photocatalysts with various weight percentages (x = 1, 3, 5, and 7 wt.%). The synthesized bare and composite photocatalysts were analyzed to illustrate their phase formation, functional group, morphology, and optical properties utilizing XRD, FT-IR, UV-Vis DRS, PL, FE-SEM, and the EDS. The photodegradation rate of MO under solar light irradiation was measured, and the 5% AgGCN composite photocatalyst showed higher photocatalytic activity (99%), which is very high compared to other bare and composite photocatalysts. The MO dye degradation rate constant with the 5% AgGCN photocatalyst exhibits 14.83 times better photocatalytic activity compared to the bare GCN catalyst. This photocatalyst showed good efficiency in the degradation of MO dye and demonstrated cycling stability even in the 5th successive photocatalytic reaction cycle. The higher photocatalytic activity of the 5% AgGCN composite catalyst for the degradation of MO dye is due to the interaction of Ag with GCN and the localized surface plasmon resonance (SPR) effect of Ag. The scavenger study results indicate that O₂^●- radicals play a major role in MO dye degradation. A possible charge-transfer mechanism is proposed to explain the solar-light-driven photocatalyst of GCN.

Comprehensive Review on g-C3N4-Based Photocatalysts for the Photocatalytic Hydrogen Production under Visible Light

Currently, the synthesis of active photocatalysts for the evolution of hydrogen, including photocatalysts based on graphite-like carbon nitride, is an acute issue. In this review, a comprehensive analysis of the state-of-the-art studies of graphic carbon nitride as a photocatalyst for hydrogen production under visible light is presented. In this review, various approaches to the synthesis of photocatalysts based on g-C₃N₄ reported in the literature were considered, including various methods for modifying and improving the structural and photocatalytic properties of this material. A thorough analysis of the literature has shown that the most commonly used methods for improving g-C₃N₄ properties are alterations of textural characteristics by introducing templates, pore formers or pre-treatment method, doping with heteroatoms, modification with metals, and the creation of composite photocatalysts. Next, the authors considered their own detailed study on the synthesis of graphitic carbon nitride with different pre-treatments and respective photocatalysts that demonstrate high efficiency and stability in photocatalytic production of hydrogen. Particular attention was paid to describing the effect of the state of the platinum cocatalyst on the activity of the resulting photocatalyst. The decisive factors leading to the creation of active materials were discussed.