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Sluggish interfacial water dissociation and the O2evolution reaction (OER) kinetics are the main obstacles that limit the photocatalytic overall water-splitting performance. A molten salt modulation of potassium–nitrogen–carbon is herein demonstrated as the formation of highly crystalline potassium-doped poly(triazine imide) (KPTI). The in situ X-ray diffraction patterns and theoretical calculation show that the KCl melt can significantly reduce the free energy for the polycondensation of triazine building blocks owing to the formation of a kinetically stable KPTI. Benefiting from the presence of potassium–carbon–nitrogen moiety, the catalyst not only weakens the excitonic confinement to improve the separation efficiency of photogenerated charge carriers but also enhances the stability of carbon sites by suppressing the undesired C═O formation. Moreover, KPTI accelerates water dissociation by forming interfacial K·H2O clusters with an ordered structure, which supplies sufficient protons for the H2evolution reaction and lowers the energy barrier to enhance the kinetics of OER. Therefore, a stable photocatalytic overall water-splitting performance can be achieved over KPTI with a stoichiometric generation of products (H2and O2). Life cycle assessment shows that a carbon-neutral scenario can be achieved on KPTI production in the near term with an increase in green power in the electricity grid.

Photocatalytic for hydrogen peroxide (H2O2) production is thought as a promising technology owing to its clean and green properties with the cheap and easily available raw materials of H2O and O2. Herein, Pt/g-C3N4Schottky junction photocatalysts with ultralow Pt contents (0.025–0.1 wt %) were successfully fabricated by an impregnation-reduction method. It can efficiently reduce O2to generate H2O2without a sacrificial agent under visible-light irradiation. The yield of H2O2produced over Pt0.05/g-C3N4with the optimal 0.05 wt % Pt reached 31.82 µM, which was 2.46 times that of g-C3N4and higher than most of those in the literature. It also showed good stability in three repeated tests. The deposition of highly dispersed metal Pt nanoparticles with low and limited content can expose enough active Pt atoms, significantly enhance the separation efficiency of photogenerated carriers, and reduce its negative effect on H2O2decomposition, resulting in improved and outstanding efficiency of H2O2production. The ·O2–radicals were found to be the main active species. The mechanism of photocatalytic H2O2production was confirmed to be a two-step single electron route (O2+ e–? ·O2–? H2O2).

Formaldehyde (HCHO) is one of the major pollutants in indoor air and long-term exposure to HCHO even at very low concentrations is harmful and may cause health problems including nasal tumors and skin irritation. Removal of HCHO is necessary to improve the quality of indoor air. Catalytic oxidative decomposition of HCHO at room temperature is regarded as the most promising strategy for the removal of HCHO because it is environmentally friendly and energy-saving. In this review, the reported catalytic materials for room-temperature catalytic oxidative decomposition of HCHO are discussed. In addition, the development and performance of catalysts for HCHO oxidative decomposition, the mechanism of this catalytic process, the surface chemistry and structure factors influencing catalytic performances, existing challenges in the development of catalysts with low cost and high activity and perspectives for important topics of future research in this area were reviewed.