O-doped and nitrogen vacancies 3D C3N4 activation of peroxydisulfate for pollutants degradation and transfer hydrogenation of nitrophenols with water

A three-dimensional carbon nitride co-modified through oxygen doping and nitrogen vacancies was prepared via an ordinary hydrothermal and thermal polymerization reaction of dicyandiamide and polyethylene glycolpolypropylene glycol-polyethylene glycol triblock copolymer (PEPE-C3N4). The electronic structure of carbon and nitrogen was proven through solid-state nuclear magnetism and electron loss energy spectroscopy. Density functional theory calculations revealed reduced band gap and altered charge density. The results show that the PEPE-C3N4 constructed by O-doped and nitrogen vacancy released electrons to activate peroxodisulfate (PDS), in which the 1% PEPE-C3N4 in the photocatalytic PDS system showed about 12 and 30 times increase of the photodegradation of 2-mercaptobenzothiazole (MBT) and bisphenol A (BPA), respectively, compared to graphite-phase carbon nitride (g-C3N4). The degradation products of MBT and BPA were named according to applying liquid chromatography-mass spectrometry and conceivable degradation pathways proposed. Furthermore, 1% PEPE-C3N4 had the highest hydrogen production activity (8275.74 mu mol center dot h- 1 center dot g- 1); it completely hydrogenates 4-nitrophenol to 4-aminophenol after 2.5 h of simulated sunlight. Additionally, biomass was used instead of TEOA to measure the coupling operation of H2 generation and selective oxidation of 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxaldehyde (DFF). The optimized PEPE-C3N4 demonstrated high efficiency for selective oxidation of HMF to DFF with simultaneous H2 co-production (1176.84 mu mol center dot h- 1 center dot g- 1 for H2 and 357.67 mu mol center dot h- 1 center dot g- 1 for DFF), 5.31 and 2.36 times more excellent than that of g-C3N4, respectively. This study outlines a way to devise photocatalysts for organic pollutant degradation and biomass value-added co-production of hydrogen.