BiOBr_0.75I_0.25/BiOIO₃ as a Novel Heterojunctional Photocatalyst with Superior Visible-Light-Driven Photocatalytic Activity in Removing Diverse Industrial Pollutants

A series of novel heterojunctional photocatalysts BiOBr_0.75I_0.25/BiOIO₃ were synthesized by a facile deposition–precipitation method for the first time. In contrast to pristine BiOIO₃, the photoabsorption of BiOBr_0.75I_0.25/BiOIO₃ composites in visible light region is greatly promoted. All the BiOBr_0.75I_0.25/BiOIO₃ composite photocatalysts exhibit highly enhanced photocatalytic activity in decomposing bisphenol A under visible light (λ > 420 nm) illumination, and the 20% BiOIO₃-BiOBr_0.75I_0.25 sample possesses the optimal photoreactivity, which is 7.4, and 3.3 times higher than those of pure BiOIO₃ and BiOBr_0.75I_0.25. Moreover, the 20% BiOIO₃-BiOBr_0.75I_0.25 sample displays superior photocatalytic performance against diverse industrial contaminants and pharmaceuticals, including methyl orange, phenol, 2,4-dichlorophenol, chlortetracycline hydrochloride, and tetracycline hydrochloride. The enhancement of phototcatalytic activity is ascribed to the profoundly promoted transfer and separation of photoexcited charge carriers, which is verified by transient photocurrent response and photoluminescence emission. In addition, the photocatalytic mechanism over composite photocatalyst under visible light irradiation is systematically investigated by active species trapping experiment and •OH quantification experiment. This work may provide a new hint for fabrication of high-performance heterojunctions by combining the narrow-band gap and wide-band gap semiconductors

Fabrication of Heterogeneous-Phase Solid-Solution Promoting Band Structure and Charge Separation for Enhancing Photocatalytic CO₂ Reduction: A Case of Zn<i>_X</i>Ca_1–<i>X</i>In₂S₄

Photocatalytic CO₂ reduction into solar fuels illustrates huge charm for simultaneously settling energy and environmental issues. The photoreduction ability of a semiconductor is closely correlated to its conduction band (CB) position. A homogeneous-phase solid-solution with the same crystal system always has a monotonously changed CB position, and the high CB level has to be sacrificed to achieve a benign photoabsorption. Herein, we report the fabrication of heterogeneous-phase solid-solution Zn<i>_X</i>Ca_1–<i>X</i>In₂S₄ between trigonal ZnIn₂S₄ and cubic CaIn₂S₄. The Zn<i>_X</i>Ca_1–<i>X</i>In₂S₄ solid solutions with orderly tuned photoresponsive range from 540 to 640 nm present a more negative CB level and highly enhanced charge-separation efficiency. Profiting from these merits, all of these Zn<i>_X</i>Ca_1–<i>X</i>In₂S₄ solid solutions exhibit remarkably strengthened photocatalytic CO₂ reduction performance under visible light (λ > 420 nm) irradiation. Zn_0.4Ca_0.6In₂S₄, bearing the most negative CB position and highest charge-separation efficiency, casts the optimal photocatalytic CH₄ and CO evolution rates, which reach 16.7 and 6.8 times higher than that of ZnIn₂S₄ and 7.2 and 3.9 times higher than that of CaIn₂S₄, respectively. To verify the crucial role of the heterogeneous-phase solid solution in promoting the band structure and photocatalytic performance, another heterogeneous-phase solid-solution Zn<i>_X</i>Cd_1–<i>X</i>In₂S₄ has been synthesized. It also displays an upshifted CB level and promoted charge separation. This work may provide a new perspective into the development of an efficient visible-light driven photocatalyst for CO₂ reduction and other photoreduction reactions

Nanocrystalline Cellulose Cures Constipation <i>via</i> Gut Microbiota Metabolism

Constipation can seriously affect the quality of life and increase the risk of colorectal cancer. The present strategies for constipation therapy have adverse effects, such as causing irreversible intestinal damage and affecting the absorption of nutrients. Nanocrystalline cellulose (NCC), which is from natural plants, has good biocompatibility and high safety. Herein, we used NCC to treat constipation assessed by the black stool, intestinal tissue sections, and serum biomarkers. We studied the effect of NCC on gut microbiota and discussed the correlation of gut microbiota and metabolites. We evaluated the long-term biosafety of NCC. NCC could effectively treat constipation through gut microbiota metabolism, which required a small dosage and did not affect the organs and intestines. NCC could be used as an alternative to medications and dietary fiber for constipation therapy

Facile <i>In Situ</i> Self-Sacrifice Approach to Ternary Hierarchical Architecture Ag/AgX (X = Cl, Br, I)/AgIO₃ Distinctively Promoting Visible-Light Photocatalysis with Composition-Dependent Mechanism

Three series of ternary hierarchical architecture photocatalysts Ag/AgX (X = Cl, Br, I)/AgIO₃ were fabricated for the first time by a facile <i>in situ</i> ion-exchange route. The novel ternary architectures are confirmed by XRD, XPS, SEM, TEM, EDX, and EDX mapping. In contrast to pristine AgIO₃, the Ag/AgX (X = Cl, Br, I)/AgIO₃ composites show extended absorption edges and highly boosted photoabsorption in the visible region, which are separately ascribed to the intrinsic absorption of AgX and the surface plasmon resonance (SPR) effect of Ag species. The photocatalysis activity of Ag/AgX (X = Cl, Br, I)/AgIO₃ composites is studied and compared <i>via</i> photodegradation of methyl orange (MO) under visible-light (λ > 420 nm) irradiation. It is interesting to find that the activity enhancement levels are different for Ag/AgX (X = Cl, Br, I)/AgIO₃ with four types of photocatalytic mechanism, which are closely related to the type of AgX or the component content in Ag/AgX (X = Cl, Br, I)/AgIO₃. The separation behaviors of charge carrier were also systematically investigated by the PL and EIS. The study may furnish new perspective into controllable fabrication of hierarchical architecture photocatalysts with multiform photocatalytic mechanism