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• 1D alkali-metal hexatitanate (AHT) nanomaterials are versatile photocatalysts for environmental and energy applications. • The state-of-the-art advancements of AHT-based photocatalysts are comprehensively reviewed. • The fundamentals, synthesis, modification and applications of AHT photocatalysts are thoroughly summarized. • The key challenges and prospects on the future directions of 1D AHT photocatalysts are also discussed. The global energy crisis and environmental problems have become two unprecedented challenges. Semiconductor photocatalysis offers a promising strategy to solve them, while its practical application requires advanced photocatalytic materials. In recent years, one-dimensional (1D) alkali-metal hexatitanate (AHT) photocatalysts have attracted considerable attention in energy and environmental fields due to their high chemical stability, excellent photoactivity, unique ion-exchange, environment-friendly, and cost-effective properties. In this review, we firstly introduce the basic properties of AHT including crystal and electronic band structure, photoactivity, and structure-property-performance relationship. Secondly, the recent advances in synthesis and modification strategies of 1D AHT photocatalysts are summarized thoughtfully, followed by a comprehensive discussion on their various environmental and energy applications, including pollutant degradation, H 2 generation, and CO 2 reduction. Finally, the key challenges and prospects are also highlighted for the development of high-performance 1D AHT-based photocatalysts for practical applications. We hope that this review will shed some light on the rational design of 1D Ti-O-based nanomaterials for efficient environmental remediation and solar fuel production. The state-of-the-art progress in 1D AHT photocatalysts, including the fundamental properties, synthesis methods, modification strategies, various environmental and energy applications, and the key challenges and prospects for their further development were comprehensively summarized. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Z-Scheme ZnIn2S4-based photocatalysts for solar-driven applications. • Various types of Z-scheme heterojunction developed recently based on ZnIn2S4 and their applications. • Potentials and limitations of ZnIn 2 S 4 photocatalyst are explored. • Mechanistic insights of ZnIn 2 S 4 based Z-scheme systems are explored. • Conclusive viewpoint and future aspects are presented. Benefiting from strong redox ability, improved charge transport, and enhanced charge separation, Z-scheme heterostructures of ZnIn 2 S 4 based photocatalysts have received considerable interest to tackle energy needs and environmental issues. The present review highlights the properties of ZnIn 2 S 4, which make it a promising photocatalyst, and a suitable combination with oxidation photocatalyst to form Z-scheme, leading to improve their photocatalytic properties dramatically. As the central part of this review, various types of Z-scheme heterojunction developed recently based on ZnIn 2 S 4 and their application in pollutant degradation, water splitting, CO 2 reduction, and toxic metals remediation. Some analytical techniques to detect or trap the active radical and study the charge separation and lifetime of charge carriers in these Z-schemes are highlighted. This review offers its readers a broad optical window for the structural architecture of ZnIn 2 S 4 -based Z-schemes, photocatalytic activity, stability, and their technological applications. Finally, we discuss the challenges and opportunities for further development on Z-Scheme ZnIn 2 S 4 -based photocatalysts toward energy and environmental applications based on the recent progress. [ABSTRACT FROM AUTHOR]

[Display omitted] • A g-C 3 N 4 /TiO 2 (CN/TOHS) hybrid with an effective hybrid structure was constructed. • The CN/TOHS hybrid exhibited exceptional performance toward the degradation of toxic pharmaceuticals. • Effective charge separation owing to large interfacial contact contributed to the high activity of the hybrid. • The CN/TOHS hybrid exhibited high stability and recyclability during consecutive test cycles. • LC/MS/MS results demonstrated the efficient mineralization of pollutants by the CN/TOHS hybrid. Herein, we rationally constructed a hybrid heterostructure comprising porous g-C 3 N 4 (CN)-encapsulated anatase TiO 2 hollow spheres (TOHS) via a synthesis method that involves hydrothermal and calcination treatments. The fabricated hybrid, termed CN/TOHS, demonstrated extraordinary activity toward the degradation of environmentally toxic pharmaceutical substances (acetaminophen and ciprofloxacin) in aqueous solutions under simulated sunlight irradiation; the activity of CN/TOHS was superior to that attained for individual TOHS and CN counterparts. In particular, the CN/TOHS hybrid containing 13.3 wt.% of CN on TOHS displayed the optimum degradation activity among the tested catalysts used in this study, and it also possessed exceptional recyclability and stability during consecutive degradation tests. The remarkable photocatalytic activity and stability of the hybrid were predominantly ascribed to the large solid interfacial contact between constituents, TOHS and CN, induced by effective hybrid structure, which boosted the interfacial charge transfer and impeded with the direct recombination of photo-induced charges. Notably, the results of the liquid chromatography–mass spectrometry analysis corroborated the effective mineralization of model pharmaceutical pollutants in the presence of the CN/TOHS hybrid. The simple interfacial engineering strategy presented in this study offers a potential route for the rational design of novel catalysts for application in environmental remediation and solar energy conversion. [ABSTRACT FROM AUTHOR]

Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride (Cl-doped g-C 3 N 4) nanorings have been designed as a superior photocatalyst for pollutant degradation and oxygen evolution reaction (OER). Remarkably, Cl-doped g-C 3 N 4 nanorings display enhanced OER performance with a small overpotential of approximately 290 mV at current density of 10 mA cm−2 and Tafel slope of 83 mV dec-1, possessing comparable OER activity to precious metal oxides RuO 2 and IrO 2 /C. The excellent catalytic performance of Cl-doped g-C 3 N 4 nanorings originates from the strong oxidation capability, abundant active sites exposed and efficient charge transfer. More importantly, visible light irradiation gives rise to a prominent improvement of the OER performance, reducing the OER overpotential and Tafel slope by 140 mV and 28 mV dec-1, respectively, demonstrating the striking photo-responsive OER activity of Cl-doped g-C 3 N 4 nanorings. The great photo-induced improvement in OER activity would be related to the efficient charge transfer and the OH radicals arising spontaneously on CN-Cl 100 catalyst upon light irradiation. This work establishes Cl-doped g-C 3 N 4 nanorings as a highly competitive metal-free candidate for photoelectrochemical energy conversion and environmental cleaning application. [ABSTRACT FROM AUTHOR]