Facile preparation of KBiO₃/g‐C₃N₄composites with microwave irradiation for photocatalytic hydrogen production

Abstract

BACKGROUND: KBiO 3 /g-C 3 N 4 composites were prepared under microwave irradiation to different weight ratios of KBiO 3 (5, 10, 20, 30, 40, 50, 60, 70 80, 90%wt) using a Mars-6 microwave for 30 min at 100 W. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS)-mapping, N 2 physisorption and diffuse reflection spectroscopy (DRS). The photocatalytic activity of the samples was evaluated in the hydrogen evolution reaction. RESULTS:The composites were confirmed by XRD, where it was observed that in samples with up to 60% KBiO 3 it is easy to identify the characteristic peak of g-C 3 N 4 . Composites show that KBiO 3 was homogeneously dispersed on g-C 3 N 4 according to EDS-mapping observations. In the photocatalytic tests it was observed that when the concentration of g-C 3 N 4 was greater than that of KBiO 3 , but up to a certain limit, there was greater production of hydrogen. CONCLUSIONS: KBiO 3 /g-C 3 N 4 composites were prepared successfully with microwave irradiation, reaching a good synergy between both materials for hydrogen production reaction. This synergy was improved by the use of microwaves that facilitate the dispersion and binding of both materials. The sample with best hydrogen production was 40%KBiO 3 /60%C 3 N 4 with 698 mol H 2 g −1 , which is about three times higher than that of g-C 3 N 4 and seven times higher than that of KBiO 3 .

Comprehensive review and future perspectives on the photocatalytic hydrogen production

“…A wide variety of semiconductor photocatalysts has been investigated so far, such as chalcogenides (ZnS, CdS, CdSe), metal oxides (TiO 2 , Cu 2 O, ZrO 2 ), carbonaceous materials (g‐C 3 N 4 ) and solid solutions [(Ga 1‐x Zn x )(N 1‐x O x ), (AgIn) x Zn 2(1‐x) S 2 ] . However, TiO 2 is still the most widely used photocatalyst because of its good stability in a wide range of pH conditions, resistance to photo‐corrosion, nontoxicity and commercial availability.…”

Photochemical Synthesis of Porous Triazine‐/Heptazine‐Based Carbon Nitride Homojunction for Efficient Overall Water Splitting

“…The band in the range of 3000–3600 cm −1 is ascribed to the stretching vibrational absorptions of N−H and intermolecular hydrogen bonding [21] . In the spectra of THCN‐24‐A and THCN‐36‐A, the characteristic peaks at 3425 and 3475 cm −1 can be assigned to the vibration band of the −NH 2 group originated from unreacted melamine raw material [22] . Compared with THCN‐24‐A, the peak intensity of −NH 2 species in THCN‐36‐A declines, and the peak disappears for THCN‐48‐A and THCN‐48‐E, indicating a complete polymerization of melamine and cyanuric trichloride precursors after 48 h UV illumination.…”

“…[21] In the spectra of THCN-24-A and THCN-36-A, the characteristic peaks at 3425 and 3475 cm À 1 can be assigned to the vibration band of the À NH 2 group originated from unreacted melamine raw material. [22] Compared with THCN-24-A, the peak intensity of À NH 2 species in THCN-36-A declines, and the peak disappears for THCN-48-A and THCN-48-E, indicating a complete polymerization of melamine and cyanuric trichloride precursors after 48 h UV illumination. The band at 570 cm À 1 corresponded to the vibration of CÀ Cl species, illustrating that a part of Cl atoms is bound to C atoms in the triazine/heptazine ring for THCN-x-y.…”

In focus: materials and the environment symposium (XXVII IMRC México)

“…In this In Focus edition of the Materials and the Environment Symposium , 11 articles were selected for publication among all the amazing work that was presented during this event. This In Focus includes articles on the production of photocatalysts for the degradation of pollutants such as herbicides, as well as the use of sugar cane bagasse and coal fly ash for the production of adsorbent materials, and the production of materials with enhanced water adsorption for agricultural applications.…”