Fabrication of a Novel SnO2 Photonic Crystal Sensitized by CdS Quantum Dots and Its Enhanced Photocatalysis under Visible Light Irradiation

Engineered inverse opal structured semiconductors for solar light-driven environmental catalysis

Inverse opal (IO) macroporous semiconductor materials with unique physicochemical advantages have been widely used in solar-related environmental areas. In this minireview, we first summarize the synthetic methods of IO materials, emphasizing the two-step and three-step approaches, with the typical physicochemical properties being compared where applicable. We subsequently discuss the application of IO semiconductors (e.g., TiO₂, ZnO, g-C₃N₄) in various photo-related environmental techniques, including photo- and photoelectro-catalytic organic pollutant degradation in water, optical sensors for environmental monitoring, and water disinfection. The engineering strategies of these hierarchical structures for optimizing the activities for different catalytic reactions are discussed, ranging from heterojunction construction, cocatalyst loading, and heteroatom doping, to surface defect construction. Structure-activity relationships are established correspondingly. With a systematic understanding of the unique properties and catalytic activities, this review is expected to orient the design and structure optimization of IO semiconductor materials for photo-related performance improvement in various environmental techniques. Finally, the challenges of emerging IO structured semiconductors and future development directions are proposed.

Cu2+doped TiO2-SiO2with photonic crystal structure for synergistic enhancement of photocatalytic degradation under visible light irradiation

The development of visible light photocatalysts with the ability to efficiently degrade pollutants is an important measure to solve environmental problems. In this paper, Cu²⁺doped TiO₂-SiO₂(CTS) with photonic crystal structure composite was successfully synthesized via sol-gel strategy and template method. The prepared materials have abundant pore structure and uniform pore diameter, and the pores were arranged in a periodically hexagonal structure. It showed enhancing synergistic effect of adsorption-photodegradation ability for removing Rhodamine B (RhB). The brilliant adsorption capability of the catalyst is not only due to the addition of silica which can increase surface area that results the increase in adsorption ability, but also related to the rich and ordered porous structure provided by the photonic crystal. The catalyst has a narrow band gap ∼2.92 eV which exhibits the excellent photocatalytic activity for RhB degradation (>95% at 30 min) under visible light irradiation, and possesses higher photocatalytic reaction apparent rate constants (k) which is 7 folds higher than that of pure TiO₂. The excellent photocatalytic performance is attributed to the Cu²⁺doping that narrows the band gap, increases light absorption, and promotes charge separation. Besides, the constructed photonic crystal structure not only further enhances charge transport but also provides more surface activity sites for photocatalytic reactions. More importantly, the ordered pore structure-photonic crystal can prolong the interaction time between light and catalyst through the slow photon effect and the porous scattering effect. Eventually, the photocatalytic degradation efficiency of the catalyst was significantly improved by the synergistic effect of the above mechanisms.

Bandgap engineering of TiO2nanotube photonic crystals for enhancement of photocatalytic capability

TiO₂nanotube photonic crystals with a tunable photonic band gap were constructed by the anodization technique and used as efficient photocatalytic devices.

Quantum dot-decorated semiconductor micro- and nanoparticles: A review of their synthesis, characterization and application in photocatalysis

Quantum dot (QD)-decorated semiconductor micro- and nanoparticles are a new class of functional nanomaterials that have attracted considerable interest for their unique structural, optical and electronic properties that result from the large surface-to-volume ratio and the quantum confinement effect. In addition, because of QDs' excellent light-harvesting capacity, unique photoinduced electron transfer, and up-conversion behaviour, semiconductor nanoparticles decorated with quantum dots have been used widely in photocatalytic applications for the degradation of organic pollutants in both the gas and aqueous phases. This review is a comprehensive overview of the recent progress in synthesis methods for quantum dots and quantum dot-decorated semiconductor composites with an emphasis on their composition, morphology and optical behaviour. Furthermore, various approaches used for the preparation of QD-based composites are discussed in detail with respect to visible and UV light-induced photoactivity. Finally, an outlook on future development is proposed with the goal of overcoming challenges and stimulating further research into this promising field.

Efficient light harvesting over a CdS/In2O3 photonic crystal photocatalyst for hydrogenation of 4-nitroaniline to p-phenylenediamine

Efficient light harvesting was observed over CdS photodeposited on In₂O₃ photonic crystals during the photocatalytic hydrogenation of 4-nitroaniline to p-phenylenediamine.

A photoelectrochemical methanol fuel cell based on aligned TiO2 nanorods decorated graphene photoanode

We report the photoelectrochemical (PEC) oxidation of methanol on a rationally designed graphene-TiO₂ nanorod array (G-TNR) photoanode.

Synthesis and characterization of UV upconversion material Y2SiO5:Pr3+, Li+/TiO2 with enhanced the photocatalytic properties under a xenon lamp

The upconversion luminescence agents Y₂SiO₅:Pr³⁺, Li⁺, that can be effectively excited by the blue light from a xenon lamp 150 W, are fabricated by a hydrothermal method with mesoporous molecular sieves of MCM-48 as the suitable silica source.