Macroscopic graphitic carbon nitride monolith for efficient hydrogen production by photocatalytic reforming of glucose under sunlight

Potential of Carbon Aerogels in Energy: Design, Characteristics, and Applications

In energy applications, the use of materials with hierarchical porous structures and large surface areas is essential for efficient charge storage. These structures facilitate rapid electron and ion transport, resulting in high power density and quick charge/discharge capabilities. Carbon-based materials are extensively utilized due to their tunable properties, including pore sizes ranging from ultra- to macropores and surface polarity. Incorporating heteroatoms such as nitrogen, oxygen, sulfur, phosphorus, and boron modifies the carbon structure, enhancing electrocatalytic properties and overall performance. A hierarchical pore structure is necessary for optimal performance, as it ensures efficient access to the material's core. The microstructure of carbon materials significantly impacts energy storage, with factors like polyaromatic condensation, crystallite structure, and interlayer distance playing crucial roles. Carbon aerogels, derived from the carbonization of organic gels, feature a sponge-like structure with large surface area and high porosity, making them suitable for energy storage. Their open pore structure supports fast ion transfer, leading to high energy and power densities. Challenges include maintaining mechanical or structural integrity, multifunctional features, and scalability. This review provides an overview of the current progress in carbon-based aerogels for energy applications, discussing their properties, development strategies, and limitations, and offering significant guidance for future research requirements.

Comprehensive Insights and Advancements in Gel Catalysts for Electrochemical Energy Conversion

Continuous worldwide demands for more clean energy urge researchers and engineers to seek various energy applications, including electrocatalytic processes. Traditional energy-active materials, when combined with conducting materials and non-active polymeric materials, inadvertently leading to reduced interaction between their active and conducting components. This results in a drop in active catalytic sites, sluggish kinetics, and compromised mass and electronic transport properties. Furthermore, interaction between these materials could increase degradation products, impeding the efficiency of the catalytic process. Gels appears to be promising candidates to solve these challenges due to their larger specific surface area, three-dimensional hierarchical accommodative porous frameworks for active particles, self-catalytic properties, tunable electronic and electrochemical properties, as well as their inherent stability and cost-effectiveness. This review delves into the strategic design of catalytic gel materials, focusing on their potential in advanced energy conversion and storage technologies. Specific attention is given to catalytic gel material design strategies, exploring fundamental catalytic approaches for energy conversion processes such as the CO2 reduction reaction (CO2RR), oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and more. This comprehensive review not only addresses current developments but also outlines future research strategies and challenges in the field. Moreover, it provides guidance on overcoming these challenges, ensuring a holistic understanding of catalytic gel materials and their role in advancing energy conversion and storage technologies.

Carbon Nitrides from Supramolecular Crystals: From Single Atoms to Heterojunctions and Advanced Photoelectrodes

Carbon nitride materials (CN) have become one of the most studied photocatalysts within the last 15 years. While CN absorbs visible light, its low porosity and fast electron-hole recombination hinder its photoelectric performance and have motivated the research in the modification of its physical and chemical properties (such as energy band structure, porosity, or chemical composition) by different means. In this Concept we review the utilization of supramolecular crystals as CN precursors to tailor its properties. We elaborate on the features needed in a supramolecular crystal to serve as CN precursor, we delve on the influence of metal-free crystals in the morphology and porosity of the resulting materials and then discuss the formation of single atoms and heterojunctions when employing a metal-organic crystal. We finally discuss the performance of CN photoanodes derived from crystals and highlight the current standing challenges in the field.

Hydrogen production via photoreforming of wastewater under LED light-driven over CuO@exfoliated g-C3N4 nanoheterojunction

As the global interest heading towards net zero emission by 2050, clean hydrogen production technologies becomes limelight among the research community. Besides, the generation of large quantity of industrial wastewaters creates huge dilemma and needs special attention. In this work, synthetic wastewater using formaldehyde (FA) as a model organic pollutant was utilized to produce hydrogen. The photocatalyst, CuO@exfoliated g-C₃N₄ nanoheterojunction was synthesized by an acid treatment and facile chemical precipitation technique. XRD results confirmed the successful formation of exfoliated g-C₃N₄ by expanding the interlayer spacing of the nanosheets via shifting of characteristic peak of graphite towards lower 2θ from 27.97° to 27.04°. Meanwhile, the BET surface area of CuO@exfoliated g-C₃N₄ (199.3 m²/g) was remarkably enhanced as compared to bulk g-C₃N₄ (34.5 m²/g) and exfoliated g-C₃N₄ (104.4 m²/g). The existence of large pores (3.55 cm³/g) in CuO@exfoliated g-C₃N₄ promotes the accessibility of reactant to the surface active sites, escalating the redox reactions. Study on hydrogen production via photoreforming of aqueous formaldehyde over the prepared photocatalysts were conducted. Interestingly, hydrogen generated using CuO@exfoliated g-C₃N₄ (3867 μmol/g) was greatly enhanced by 7 times and 13 times than the counterparts catalysts, exfoliated g-C₃N₄ (532 μmol/g) and pure CuO (271 μmol/g) respectively. By employing the CuO@exfoliated g-C₃N₄ nanoheterojunction, the optimum hydrogen with apparent quantum efficiency (AQE) of 5664 μmol/g and 22% were obtained respectively. Besides, S-scheme reaction mechanism was proposed based on heterojunction formed between the p-type CuO and n-type exfoliated g-C₃N₄ nanosheets.