Enhanced UV–Vis–NIR composite photocatalysis of NaBiF4:Yb3+, Tm3+ upconversion nanoparticles loaded on Bi2WO6 microspheres

Upconversion boosting pollutants degradation efficiency in wide-spectrum responsive photocatalysts

Recently, the composite photocatalysts coupled with upconversion materials have received widespread attention due to higher utilization efficiency of solar energy in a wide-spectrum range. Novel heterojunction photocatalysts of CoWO₄@NaYF₄:Yb³⁺,Er³⁺ were designed and developed herein. The structural characterization, morphology and elemental composition analysis demonstrated that heterojunctions between CoWO₄ and NaYF₄:Yb³⁺,Er³⁺ were indeed formed in the composite photocatalysts. Moreover, CoWO₄@NaYF₄:Yb³⁺,Er³⁺ heterojunction photocatalysts exhibited higher pollutants degradation efficiency. Especially, a great enhancement of +87% on the photocatalytic activity was achieved in the heterojunction photocatalyst of 60CoWO₄-NaYF₄:Yb³⁺,Er³⁺ compared with pure CoWO₄. The dominant radicals generated from the heterojunction photocatalysts were confirmed as the photo-generated holes (h⁺) and hydroxyl radicals (⋅OH) through the radical species trapping experiments and fluorescence detection, which is fully in line with the expected band structure characteristics of CoWO₄. Eventually, an underlying mechanism was proposed that the enhanced photocatalytic activity should be attributed to the wide-spectrum responsive features of CoWO₄@NaYF₄:Yb³⁺,Er³⁺ heterojunction photocatalysts. Within the heterostructures, CoWO₄ photocatalyst can absorb both the UV-Vis light due to its narrow bandgap and the Near-Infrared energy through the upconversion NaYF₄:Yb³⁺,Er³⁺, thereby utilizing solar energy more efficiently in a wide-spectrum range for photocatalytic reactions.

Strategies based review on near-infrared light-driven bismuth nanocomposites for environmental pollutants degradation

Recently, solar energy has been considered the most vulnerable source to resolve environmental pollution and energy scarcity problems. Researchers have made intense research efforts to convert solar energy into chemical energy through photocatalysis processes as it is a green, clean and renewable energy source. Numerous discovered photocatalysts show absorption in the ultraviolet-visible (UV∼5% and visible ∼43%) region and are devoid of near-infrared (NIR ∼52%) light utilization. As infrared (IR) light contains a top portion of the solar spectrum; therefore, many alluring and attractive practical strategies have been explored to improve photocatalytic reactions and to harness full solar spectrum (including NIR light). Among those strategies, bandgap engineering, coupling with carbon quantum dots, heterostructure formation, mingling with plasmonic and upconversion (UC) NPs are more worthwhile. In different visible light-assisted photocatalysts, bismuth typically covers a distinctive, favorable, and earth-abundant group of freshly discovered innovative photocatalytic nanomaterials. Bi-based photocatalysts have suitable/good optoelectronic properties, crystalline geometric conformations, amendable electronic structure, and outstanding visible-light responsive range, helpful in environmental remediation and energy transformation. Due to the outstanding photo-oxidization/photodegradation capability of NIR-driven photocatalysts, bismuth-based nanomaterials have been considered suitable photocatalysts for inclusive solar energy utilization. Henceforth, keeping in mind the benefits of bismuth nanomaterials, the present review is focused on NIR-based modification strategies to upgrade solar light absorption of bismuth-based photocatalysts in the NIR region by making it NIR responsive photocatalyst. We have also discussed the photocatalytic applications of bismuth-based NIR responsive photocatalysts in pollutant degradation.

Multiphoton Upconversion Materials for Photocatalysis and Environmental Remediation

Solar-driven photocatalysis holds great potential for energy conversion, environmental remediation, and sustainable chemistry. However, practical applications of conventional photocatalytic systems have been constrained by their insufficient ability to harvest solar radiation in the infrared spectrum. Lanthanide-doped upconversion materials possess high photostability, tunable absorption, and the ability to convert low-energy infrared radiation into high-energy emission, making them attractive for infrared-driven photocatalysis. This review highlights essential principles for rational design of efficient photocatalysts. Particular emphasis is placed on current state-of-the-arts that offer enhanced upconversion luminescence efficiency. We also summarize recent advances in lanthanide-doped upconversion materials for photocatalysis. We conclude with new challenges and prospects for future developments of infrared-driven photocatalysts.