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As a promising photocatalyst material, g-C 3 N 4 has great application potential in energy production and environmental improvement. In this work, surface-modified g-C 3 N 4 nanosheets with excellent stability and high photocatalytic activity were successfully synthesized by physical steam activation. The charge transfer rate of carbon nitride was improved due to the synergistic effect of nitrogen defect and oxygen doping caused by steam activation. Meanwhile, the specific surface area and pore volume of the optimized sample reached 124.3 m 2 g −1 and 0.42 cm 3 g −1 , respectively, which increased the exposed reaction sites of reactants, enhancing the photocatalytic activity of g-C 3 N 4 . In addition, this novel g-C 3 N 4 displayed a great H 2 evolution rate of 5889.39 μmol h −1 g −1 with a methylene blue degradation rate up to 6.52 × 10 −3 min −1 , which was 3.7 and 2.1 times of original g-C 3 N 4 , respectively. This study provided a simple and economical method to develop a highly efficient g-C 3 N 4 photocatalyst for solar energy conversion.

Biomineral materials such as nacre of shells exhibit high mechanical strength and toughness on account of their unique “brick-mortar” multilayer structure. 2-Ureido-4­[1H]-pyrimidinone (UPy) derivatives with different types of end groups, due to the self-complementary quadruple hydrogen bonds and abundant Ca2+ binding sites, can easily self-assemble into supramolecular aggregates and act as templates and skeleton in the process of inducing mineral crystallization. In this work, UPy derivatives were used as templates to induce the mineralization and growth of CaCO3 through a CO2 diffusion method. The morphology of CaCO3 crystals was modulated and analyzed by adjusting the synthesizing parameters including Ca2+ concentration, pH, and end groups. The results showed that, by the regulatory role of the mineralization template, it was easier to realize the multilayer crystal structure at a lower concentration of Ca2+ (less than 0.01 mol L–1). Under alkaline regulation, the quadruple hydrogen bonds would be destroyed, and the template’s regulation effect on the morphology of CaCO3 crystals would be weakened. Moreover, by comparing different types of end groups, it was proven that the UPy derivatives with carboxylic acid groups (−COOH) played a crucial role in the process of CaCO3 crystallization with unique morphologies.

Carbon-based supercapacitors with high performance have a wide foreground among various energy storage devices. In this work, wood-based hollow carbon spheres (WHCS) were prepared from liquefied wood through the processes of emulsification, curing, carbonization, and activation. Then, the hydrodeposition method was used to introduce nickel sulfide (NiS) to the surface of the microspheres, obtaining NiS/WHCS as the supercapacitor electrode. The results show that NiS/WHCS microspheres exhibited a core–shell structure and flower-like morphology with a specific surface (307.55 m2 g–1) and a large total pore volume (0.14 cm3 g–1). Also, the capacitance could be up to 1533.6 F g–1 at a current density of 1 A g–1. In addition, after 1000 charge/discharge cycles, the specific capacitance remained at 72.8% at the initial current density of 5 A g–1. Hence, NiS/WHCS with excellent durability and high specific capacitance is a potential candidate for electrode materials.

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