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In this study, a series of CuO/CdS composites were synthesized by thermal oxidation and successive ionic layer adsorption and reaction (SILAR). The as-prepared CuO/CdS composites were investigated by x-ray diffraction (XRD), field emission high-resolution scanning electron microscopy (FESEM) and energy-dispersive spectrometry. Their photocatalytic activity was investigated by monitoring the degradation of methylene blue (MB) under ultraviolet and visible light irradiation. The XRD pattern indicated that the precursor was cubic-phase CuO and Cu2O. FESEM results indicate that changes in annealing time and temperature have an effect on morphology, but the nanowire structures are preserved. The growth mechanism of the CuO nanowires is discussed in detail. Furthermore, the photocatalytic degradation rate of the MB, determined using an ultraviolet-visible spectrophotometer (UV-vis, UV-2600, Shimadzu), indicates that CdS can significantly improve the absorption of visible light from the sun. [ABSTRACT FROM AUTHOR]

Samples of biochar-coupled g-C 3 N 5 /C have been prepared using 3-amino-1,2,4-triazole and peanut oil as precursors to increase the specific surface area of g-C 3 N 5. The results showed that the specific surface area of g-C 3 N 5 /C-1.0 reached 44.7 m2 g−1, and the C/N ratio increased from 0.56 to 1.48. The weakness of its photoluminescence (PL) peak confirmed that g-C 3 N 5 /C-1.0 had the best separation of photogenerated electrons and holes. Furthermore, the fluorescence lifetime of g-C 3 N 5 /C-1.0 is extended to 6.4 ns, compared to 2.9 ns for g-C 3 N 5. Therefore, g-C 3 N 5 /C-1.0 displays superior photocatalytic activity to that of pure g-C 3 N 5 under visible-light irradiation. This is because the large specific surface area leads to increased absorption of visible light and efficient separation of electron–hole pairs. The hydrogen evolution rate of g-C 3 N 5 /C-1.0 is 303.3 μmol g−1 h−1 (cf. 67.5 μmol g−1 h−1 for g-C 3 N 5), and the photodegradation efficiency of rhodamine B (RhB) is as high as 93.7% (cf. 26.1% for g-C 3 N 5). Sample g-C 3 N 5 /C-1.0 also maintained outstanding photocatalytic stability after four cycles. Radical scavenger experiments and ESR tests have shown •O 2 − to be the main reactive species responsible for RhB degradation under visible light. • Biochar-doped g-C 3 N 5 was synthesized by one-step method with peanut oil as biochar source. • Biochar-doped g-C 3 N 5 can improve the specific surface area and light absorption ability. • g-C 3 N 5 /C-1.0 exhibited H 2 evolution of 303.3 μmol g−1 h−1, which was 4.5 times than that of pure g-C 3 N 5. • The photodegradation to rhodamine B of g-C 3 N 5 /C-1.0 can reach 93.7% after 150 min. • The g-C 3 N 5 /C-1.0 has good photocatalytic activity and chemical stability. [ABSTRACT FROM AUTHOR]