Homogeneous dual-site P lattice doping in CdS quantum rods for visible-light photocatalytic water splitting

Recent progress in defect-engineered metal oxides for photocatalytic environmental remediation

Rapid industrial advancement over the last few decades has led to an alarming increase in pollution levels in the ecosystem. Among the primary pollutants, harmful organic dyes and pharmaceutical drugs are directly released by industries into the water bodies which serves as a major cause of environmental deterioration. This warns of a severe need to find some sustainable strategies to overcome these increasing levels of water pollution and eliminate the pollutants before being exposed to the environment. Photocatalysis is a well-established strategy in the field of pollutant degradation and various metal oxides have been proven to exhibit excellent physicochemical properties which makes them a potential candidate for environmental remediation. Further, with the aim of rapid industrialization of photocatalytic pollutant degradation technology, constant efforts have been made to increase the photocatalytic activity of various metal oxides. One such strategy is the introduction of defects into the lattice of the parent catalyst through doping or vacancy which plays a major role in enhancing the catalytic activity and achieving excellent degradation rates. This review provides a comprehensive analysis of defects and their role in altering the photocatalytic activity of the material. Various defect-rich metal oxides like binary oxides, perovskite oxides, and spinel oxides have been summarized for their application in pollutant degradation. Finally, a summary of existing research, followed by the existing challenges along with the potential countermeasures has been provided to pave a path for the future studies and industrialization of this promising field.

Facile construction of a robust CuS@NaNbO3 nanorod composite: A unique p-n heterojunction structure with superior performance in photocatalytic hydrogen evolution

The construction of heterojunctions is commonly regarded as an efficient way to promote the production of hydrogen via photocatalytic water splitting through the enhancement of interfacial interactions. The p-n heterojunction is an important kind of heterojunction with an inner electric field based on the different properties of semiconductors. In this work, we reported the synthesis of a novel CuS/NaNbO₃ p-n heterojunction by depositing CuS nanoparticles on the external surface of NaNbO₃ nanorods, using a facile calcination and hydrothermal method. Through the screening of different ratios, the optimum hydrogen production activity reached 1603 μmol·g^-1·h^-1, which is much higher than that of NaNbO₃ (3.6 times) and CuS (2.7 times). Subsequent characterizations proved semiconductor properties and the existence of p-n heterojunction interactions between the two materials, which inhibited the recombination of photogenerated carriers and improved the efficiency of electron transfer. This work provides a meaningful strategy to utilize the p-n heterojunction structure for the promotion of photocatalytic hydrogen production.

Preparation of P-doped CdS nanorods as an efficient photocatalyst for the degradation of the emerging pollutant tetracycline antibiotic under blue LED light irradiation

Excessive drug usage and sewage discharges containing antibiotics have caused water contamination due to the rapid growth of pharmaceutical industries. Tetracycline (TC) is one of the most frequently applied antibiotics having a significant impact on the aquatic environment, water quality and human health and thus effective approaches for TC removal from water are urgently needed. Here, we have fabricated P-doped CdS (CdS-P_0.8) nanorods (NRs) by one-step thermal phosphorization treatment for TC degradation through photocatalytic reaction in the presence of blue and white LED light irradiation. Synthesized photocatalysts were characterized to authenticate the incorporation of P atoms on the CdS NR surface using XPS, XRD, ICP-OES and EDX mapping analyses. CdS-P_0.8 NRs have greater photocatalytic activity for tetracycline degradation under blue LED light irradiation. TC degradation on CdS-P_0.8 NRs followed pseudo-first order kinetics for both LED light sources. In the presence of blue LED light at an intensity of 10 mW cm^-2, TC degradation efficiency and pseudo-first order rate constants of CdS-P_0.8 NRs for the photocatalytic degradation reaction reached 95.4% and 0.13396 min^-1 in 20 minutes without any supplemental oxygen sources. Scavenging experiments demonstrate that reactive oxygen species are produced during the photocatalytic degradation of tetracycline. As a result, due to the extensive utilization of photogenerated oxidative species such as h⁺, O₂˙^- and OH˙, CdS-P_0.8 NRs demonstrated high photocatalytic tetracycline degradation efficiency in 20 minutes. Our findings shed more light on nonmetal P doping on CdS materials and other semiconductors, exploring new possibilities for photocatalytic degradation to efficiently reduce the amount and toxicity of TC antibiotics in wastewater.

Facile and Robust Construction of 3D-Hierarchical NaNbO3-Nanorod/ZnIn2S4 Heterojunction toward Ultra-high Photocatalytic H2 Production

It is quite imperative yet remained challenging to develop the heterojunction photocatalysts for efficient interfacial charge carriers separation on photocatalytic hydrogen evolution (PHE) reactions. Encouragingly, in this work, we constructed...

Robust visible-light photocatalytic H2 evolution on 2D RGO/Cd0.15Zn0.85In2S4–Ni2P hierarchitectures

Unique 2D ternary hierarchitectures constructed from reduced graphene oxide nanosheets grown with ultrathin Cd0.15Zn0.85In2S4 nanosheets and Ni2P nanoparticles exhibited an outstanding capability for visible-light photocatalytic H2 production.