Photosynthesis of Hydrogen Peroxide Based on g-C3 N4 : The Road of a Cost-Effective Clean Fuel Production

Promoting Proton Donation through Hydrogen Bond Breaking on Carbon Nitride for Enhanced H2O2 Photosynthesis

Photocatalytic H2O2 production has attracted much attention as an alternative way to the industrial anthraquinone oxidation process but is limited by the weak interaction between the catalysts and reactants as well as inefficient proton transfer. Herein, we report on a hydrogen-bond-broken strategy in carbon nitride for the enhancement of H2O2 photosynthesis without any sacrificial agent. The H2O2 photosynthesis is promoted by the hydrogen bond formation between the exposed N atoms on hydrogen-bond-broken carbon nitride and H2O molecules, which enhances proton-coupled electron transfer and therefore the photocatalytic activity. The exposed N atoms serve as proton buffering sites for the proton transfer from H2O molecules to carbon nitride. The H2O2 photosynthesis is also enhanced through the enhanced adsorption and reduction of O2 gas toward H2O2 on hydrogen-bond-broken carbon nitride because of the formation of nitrogen vacancies (NVs) and cyano groups after the intralayer hydrogen bond breaking on carbon nitride. A high light-to-chemical conversion efficiency (LCCE) value of 3.85% is achieved. O2 and H2O molecules are found to undergo a one-step two-electron reduction pathway by photogenerated hot electrons and a four-electron oxidation process to produce O2 gas, respectively. Density functional theory (DFT) calculations validate the O2 adsorption and reaction pathways. This study elucidates the significance of the hydrogen bond formation between the catalyst and reactants, which greatly increases the proton tunneling dynamics.

Synthesis of borocarbonitride nanosheets from biomass for enhanced charge separation and hydrogen production

Borocarbonitride (BCN) materials have shown significant potential as photocatalysts for hydrogen production. However, traditional bulk BCN exhibits only moderate photocatalytic activity. In this study, we introduce an environmentally conscious and sustainable strategy utilizing biomass-derived carbon sources to synthesize BCN nanosheets. The hydrogen evolution efficiency of BCN-A nanosheets (110 μmol h-1 g-1) exceeds that of bulk BCN photocatalysts (12 μmol h-1 g-1) by 9.1 times, mainly due to the increased surface area (205 m2g-1) and the presence of numerous active sites with enhanced charge separation capabilities. Notably, the biomass-derived BCN nanosheets offer key advantages such as sustainability, cost-effectiveness, and reduced carbon footprint during hydrogen production. These findings highlight the potential of biomass-based BCN nanomaterials to facilitate a greener and more efficient route to hydrogen energy, contributing to the global transition towards renewable energy solutions.

Review on Microreactors for Photo-Electrocatalysis Artificial Photosynthesis Regeneration of Coenzymes

In recent years, with the outbreak of the global energy crisis, renewable solar energy has become a focal point of research. However, the utilization efficiency of natural photosynthesis (NPS) is only about 1%. Inspired by NPS, artificial photosynthesis (APS) was developed and utilized in applications such as the regeneration of coenzymes. APS for coenzyme regeneration can overcome the problem of high energy consumption in comparison to electrocatalytic methods. Microreactors represent a promising technology. Compared with the conventional system, it has the advantages of a large specific surface area, the fast diffusion of small molecules, and high efficiency. Introducing microreactors can lead to more efficient, economical, and environmentally friendly coenzyme regeneration in artificial photosynthesis. This review begins with a brief introduction of APS and microreactors, and then summarizes research on traditional electrocatalytic coenzyme regeneration, as well as photocatalytic and photo-electrocatalysis coenzyme regeneration by APS, all based on microreactors, and compares them with the corresponding conventional system. Finally, it looks forward to the promising prospects of this technology.

A Schottky/Z-Scheme Hybrid for Augmented Photocatalytic H2 and H2O2 Production

The prodigious employment of fossil fuels to conquer the global energy demand is becoming a dreadful threat to the human society. This predicament is appealing for a potent photocatalyst that can generate alternate energy sources via solar to chemical energy conversion. With this interest, we have fabricated a ternary heterostructure of Ti3C2 nanosheet modified g-C3N4/Bi2O3 (MCNRBO) Z-scheme photocatalyst through self-assembly process. The morphological analysis clearly evidenced the close interfacial interaction between g-C3N4 nanorod, Bi2O3 and Ti3C2 nanosheets. The oxygen vacancy created on Bi2O3 surface, as suggested by XPS and EPR analysis, supported the Z-scheme heterojunction formation between g-C3N4 nanorod and Bi2O3 nanosheets. The collaborative effect of Z-scheme and Schottky junction significantly reduced charge transfer resistance promoting separation efficiency of excitons as indicated from PL and EIS analysis. The potential of MCNRBO towards photocatalytic application was investigated by H2O2 and H2 evolution reaction. A superior photocatalytic H2O2 and H2 production rate for MCNRBO is observed, which are respectively around 5 and 18 folds higher as compared to pristine CNR nanorod. The present work encourages for the development of a noble, eco-benign and immensely efficient dual heterojunction based photocatalyst, which can acts as saviour of human society from energy crisis.

Cascade Self-Generation of Carbon Monoxide Triggered by Photoinduced Holes for Efficient Hypoxic Tumors Therapy

It still remains challenging to design multifunctional therapeutic reagents for effective cancer therapy under a unique tumor microenvironment including insufficient endogenous H2O2 and O2, low pH, and a high concentration of glutathione (GSH). In this work, a CO-based phototherapeutic system triggered by photogenerated holes, which consisted of ionic liquid (IL), the CO prodrug Mn2(CO)10, and iridium(III) porphyrin (IrPor) modified carbonized ZIF-8-doped graphitic carbon nitride nanocomposite (IL/ZCN@Ir(CO)), was designed for cascade hypoxic tumors. Upon light irradiation, the photogenerated holes on IL/ZCN@Ir(CO) oxidize water into H2O2, which subsequently induces Mn2(CO)10 to release CO. Meanwhile, IrPor can convert H2O2 to hydroxyl radical (•OH) and subsequent singlet oxygen (1O2), which further triggers CO release. Moreover, the degraded MnO2 shows activity for glutathione (GSH) depletion and mimics peroxidase, leading to GSH reduction and •OH production in tumors. Thus, this strategy can in situ release high concentrations of CO and reactive oxygen species (ROS) and deplete GSH to efficiently induce cell apoptosis under hypoxic conditions, which has a high inhibiting effect on the growth of tumors, offering an attractive strategy to amplify CO and ROS generation to meet therapeutic requirements in cancer treatment.

Solar-to-H2 O2 Catalyzed by Covalent Organic Frameworks

Benefiting from the excellent structural tunability, robust framework, ultrahigh porosity, and rich active sites, covalent organic frameworks (COFs) are widely recognized as promising photocatalysts in chemical conversions, and emerged in the hydrogen peroxide (H2 O2 ) photosynthesis in 2020. H2 O2 , serving as an environmental-friendly oxidant and a promising liquid fuel, has attracted increasing researchers to explore its potential. Over the past few years, numerous COFs-based photocatalysts are developed with encouraging achievements in H2 O2 production, whereas no comprehensive review articles exist to summarize this specific and significant area. Herein we provide a systematic overview of the advances and challenges of COFs in photocatalytic H2 O2 production. We first introduce the priorities of COFs in H2 O2 photosynthesis. Then, various strategies to improve COFs photocatalytic efficiency are discussed. The perspective and outlook for future advances of COFs in this emerging field are finally offered. This timely review will pave the way for the development of highly efficient COFs photocatalysts for practical production of value-added chemicals not limited to H2 O2 .

Electrifying H2O2 synthesis with g-C3N4-based single atom catalysts

This article highlights the recent work of Zhang, Peng et al. (Nanoscale Horiz., 2023, 8, 695, https://doi.org/10.1039/D2NH00564F) on transition metal single atom embedded graphitic carbon nitride nanosheets for the neutral electrosynthesis of hydrogen peroxide.

Enhancing piezocatalytic H2O2 production through morphology control of graphitic carbon nitride

Piezocatalytic H₂O₂ production has attracted significant attention as a green alternative to traditional anthraquinone methods with heavy environmental pollution and high energy consumption. However, since the efficiency of piezocatalyst in producing H₂O₂ is poor, searching for a suitable method to improve the yield of H₂O₂ is of great interest. Herein, a series of graphitic carbon nitride (g-C₃N₄) with different morphologies (hollow nanotube, nanosheet and hollow nanosphere) are applied to enhance the piezocatalytic performance in yielding H₂O₂. The hollow nanotube g-C₃N₄ exhibited an outstanding H₂O₂ generation rate of 262 umol·g^-1·h^-1 without any co-catalyst, which is 1.5 and 6.2 times higher than nanosheets and hollow nanospheres, respectively. Piezoelectric response force microscopy, piezoelectrochemical tests, and Finite Element Simulation results revealed that the excellent piezocatalytic property of hollow nanotube g-C₃N₄ is mainly attributed to its larger piezoelectric coefficient, higher intrinsic carrier density, and stronger external stress absorption conversion. Furthermore, mechanism analysis indicated that piezocatalytic H₂O₂ production follows a two-step single-electro pathway, and the discovery of ¹O₂ furnishes a new insight into explore this mechanism. This study offers a new strategy for the eco-friendly manufacturing of H₂O₂ and a valuable guide for future research on morphological modulation in piezocatalysis.