Morphology effect of honeycomb-like inverse opal for efficient photocatalytic water disinfection and photodegradation of organic pollutant

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.

Rapidly and highly efficient degradation of tetracycline hydrochloride in wastewater by 3D IO-TiO2-CdS nanocomposite under visible light

Tetracycline hydrochloride as an environmental pollutant is biologically toxic and highly difficult to degrade. To solve this problem, an efficient catalyst IO-TiO₂-CdS composite with honeycomb-like three-dimensional (3D) inverse opal TiO₂ (IO-TiO₂) and cadmium sulphide (CdS) was synthesized and applied in the degradation of tetracycline hydrochloride in this paper. More than 99% of the tetracycline hydrochloride (30 mg/L) can be degraded by IO-TiO₂-CdS (30 mg) within 20 min under visible light irradiation. Surprisingly, the naphthol rings can be opened and degraded to alkane with a minimum molecular weight of 60, which is the smallest fragment among all publications. The three-dimensional ordered macroporous (3DOM) structure of IO-TiO₂ improves the utilization of light via the slow photon effect. Meanwhile, the addition of CdS enhances the degradation efficiency of tetracycline by broadening the range of absorption spectrum and improving the separation of charge carrier on the catalyst. In addition to the degradation of tetracycline hydrochloride, IO-TiO₂-CdS also shows a good degradation efficiency of Rhodamine B (RhB). This work provides a promising approach to construct visible light response photocatalysts with non-noble metal for efficient degradation of wastewater pollutants.

Lead Acetate Assisted Interface Engineering for Highly Efficient and Stable Perovskite Solar Cells

High power conversion efficiency (PCE) and long-term stability are inevitable issues faced in practical device applications of perovskite solar cells. In this paper, significant enhancements in the device efficiency and stability are achieved by using a surface-active lead acetate (Pb(OAc)₂) at the top or bottom of CH₃NH₃PbI₃ (MAPbI₃)-based perovskite. When a saturated Pb(OAc)₂ solution is introduced on the top of the MAPbI₃ perovskite precursor, the OAc^- in Pb(OAc)₂ participates in lattice restructuring of MAPbI₃ to form MAPbI_3-x(OAc)_x, thereby producing a high-quality perovskite film with high crystallinity, large grain sizes, and uniform and pinhole-free morphology. Moreover, when Pb(OAc)₂ solution is mixed in the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) solution in the bottom way, the OAc^- in Pb(OAc)₂ improves the water resistance of PEDOT-PSS. As the OAc^- easily bonds with the Pb²⁺, the deposition of MAPbI₃ precursor onto the Pb(OAc)₂ mixed with PEDOT-PSS results in a reduction of the uncoordinated Pb, leading to strong stabilization of the perovskite layer. Both the top- and bottom-treated devices exhibit enhanced PCE values of 18.93% and 18.28%, respectively, compared to the conventional device with a PCE of 16.47%, which originates from decreased trap sites and reduced energy barriers. In particular, the bottom-treated device exhibits long-term stability, with more than 84% of its initial PCE over 800 h in an ambient environment.

Alkaline-earth-metal-doped TiO2 for enhanced photodegradation and H2 evolution: insights into the mechanisms

The doping strategy of TiO₂ with an AM (alkali earth metal) for photocatalysis applications has been reported in several literature reports.