High-crystalline g-C 3 N 4 nanosheets (HC−CN) with reduced structural defects have been constructed through Ni-foam-induced thermal condensation because Ni-foam not only serves as a template for deposition of the 2D g-C 3 N 4 nanosheets with high surface area to prevent stacking of g-C 3 N 4 nanosheets but also acts as a catalyst to promote the polymerization and crystallization of g-C 3 N 4 via effective dehydrogenation of the −NH 2 group. The obtained HC−CN exhibits superior photocatalytic performance for H 2 evolution under visible light irradiation (λ > 400 nm), which significantly benefits from the prolonged lifetime of photogenerated charge carriers and the increase of the transfer path within 2D structures of high-crystalline g-C 3 N 4 nanosheets.

Nanosized TiO 2 containing different contents of rutile phase was controllably synthesized by a hydrochloric acid-modified hydrothermal process. It is demonstrated that the formation of rutile phase in TiO 2 mainly depends on the role of chlorine anions in the synthesis, and a certain amount of residual chloride would exist on the surfaces of the resulting nanocrystalline rutile TiO 2 . Interestingly, the as-prepared rutile shows high activity for photodegradation of rhodamine B dye compared with the as-prepared anatase, even superior to the P25 TiO 2 . It is mainly attributed to the residual chloride that could promote the dye adsorbed on the surfaces of TiO 2 , consequently accelerating the photosensitization oxidation reactions of the dye molecules. In the photodegradation of liquidphase phenol and gas-phase aldehyde, the as-prepared rutile TiO 2 samples display low activity, which is attributed to the photogenerated electrons weakly captured by the adsorbed oxygen, since the residual chloride could effectively capture photoinduced holes based on the atmosphere-controlled surface photovoltage spectroscopy results. Further, the photoactivity of resulting rutile for degrading phenol and aldehyde is greatly enhanced by modifying a proper amount of phosphoric acids to increase the adsorption of O 2 , even higher than that of the P25 TiO 2 . This work would explore feasible routes to synthesize efficient nanosized rutile TiO 2 -based photocatalysts for degrading colored and colorless organic pollutants by investigating the rate-determining factors in the photodegradation processes.

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In this study, α-Fe2O3 nanoparticles with high visible photocatalytic activity for degrading liquid-phase phenol and gas-phase acetaldehyde have been controllably synthesized by a simple one-pot water-organic two-phase separated hydrolysis-solvothermal (HST) method. Further, the visible photocatalytic activity is enhanced greatly after modification with a proper amount of phosphate. The enhanced activity is attributed to the increased charge separation by promoting photogenerated electrons captured by the adsorbed O2 by means of the atmosphere-controlled surface photovoltage spectra, along with the photoelectrochemical I–V curves. On the basis of the O2 temperature-programmed desorption measurements, it is suggested for the first time that the promotion effect results from the increase in the amount of O2 adsorbed on the surfaces of Fe2O3 by the partial substitution of −Fe–OH with −Fe–O–P–OH surface ends. Expectedly, the positive strategy would be also applicable to other visible-response nanosized oxides as efficient photocatalysts. This work will provide us with a feasible route to synthesize oxide-based nanomaterials with good photocatalytic performance.