Facile Synthesis of Surface-Modified Nanosized α‑Fe₂O₃ as Efficient Visible Photocatalysts and Mechanism Insight

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

Template-Induced High-Crystalline g‑C₃N₄ Nanosheets for Enhanced Photocatalytic H₂ Evolution

High-crystalline g-C₃N₄ 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-C₃N₄ nanosheets with high surface area to prevent stacking of g-C₃N₄ nanosheets but also acts as a catalyst to promote the polymerization and crystallization of g-C₃N₄ via effective dehydrogenation of the −NH₂ group. The obtained HC–CN exhibits superior photocatalytic performance for H₂ 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-C₃N₄ nanosheets

Synthesis of Efficient Nanosized Rutile TiO₂ and Its Main Factors Determining Its Photodegradation Activity: Roles of Residual Chloride and Adsorbed Oxygen

Nanosized TiO₂ 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 TiO₂ 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 TiO₂. 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 TiO₂. It is mainly attributed to the residual chloride that could promote the dye adsorbed on the surfaces of TiO₂, consequently accelerating the photosensitization oxidation reactions of the dye molecules. In the photodegradation of liquid-phase phenol and gas-phase aldehyde, the as-prepared rutile TiO₂ 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 O₂, even higher than that of the P25 TiO₂. This work would explore feasible routes to synthesize efficient nanosized rutile TiO₂-based photocatalysts for degrading colored and colorless organic pollutants by investigating the rate-determining factors in the photodegradation processes

Enabling Nitrogen Fixation on Bi₂WO₆ Photocatalyst by c‑PAN Surface Decoration

It remains a challenge to obtain active sites on semiconductor-based photocatalysts for nitrogen fixation. Herein, we decorate Bi₂WO₆ by cyclized polyacrylonitrile (c-PAN) to craft a hybrid photocatalyst with superior nitrogen fixation performance (160 μmol·h^–1·g^–1). The unsaturated N in c-PAN can serve as active sites to achieve strong N₂ absorption and activation. This facile approach provides new insight into the reasonable design of elegant photocatalysts with abundant active sites