Sonochemical synthesis of photocatalysts and their applications

Effect of hole doping and strain modulations on electronic structure and magnetic properties in ZnO monolayer

Anchoring transition metal elements on graphene-like ZnO monolayer by CO molecule to obtain spin gapless semiconductor

In this review, the most recent advances in the field of magnetic composite photocatalysts with integrated plasmonic silver (Ag) is presented, with an overview of their synthesis techniques, properties and photocatalytic pollutant removal applications. Magnetic attributes combined with plasmonic properties in these composites result in enhancements for light absorption, charge-pair generation-separation-transfer and photocatalytic efficiency with the additional advantage of their facile magnetic separation from water solutions after treatment, neutralizing the issue of silver’s inherent toxicity. A detailed overview of the currently utilized synthesis methods and techniques for the preparation of magnetic silver-integrated composites is presented. Furthermore, an extended critical review of the most recent pollutant removal applications of these composites via green photocatalysis technology is presented. From this survey, the potential of magnetic composites integrated with plasmonic metals is highlighted for light-induced water treatment and purification. Highlights: (1) Perspective of magnetic properties combined with plasmon metal attributes; (2) Overview of recent methods for magnetic silver-integrated composite synthesis; (3) Critical view of recent applications for photocatalytic pollutant removal.

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Magnetic Metal Oxide-Based Photocatalysts with Integrated Silver for Water Treatment

2D materials van der Waals heterostructures (vdWHs) provide a revolutionary route toward high‐performance solar energy conversion devices beyond the conventional silicon‐based pn junction solar cells. Despite tremendous research progress accomplished in recent years, the searches of vdWHs with exceptional excitonic solar cell conversion efficiency and optical properties remain an open theoretical and experimental quest. Here, this study shows that the vdWH family composed of MoSi2N4 and WSi2N4 monolayers provides a compelling material platform for developing high‐performance ultrathin excitonic solar cells and photonics devices. Using first‐principle calculations, 51 types of MoSi2N4 and WSi2N4‐based [(Mo,W)Si2N4] vdWHs composed of various metallic, semimetallic, semiconducting, insulating, and topological 2D materials are constructed and classified. Intriguingly, MoSi2N4/(InSe, WSe2) are identified as Type II vdWHs with exceptional excitonic solar cell power conversion efficiency reaching well over 20%, which are competitive to state‐of‐the‐art silicon solar cells. The (Mo,W)Si2N4 vdWH family exhibits strong optical absorption in both the visible and UV regimes. Exceedingly large peak UV absorptions over 40%, approaching the maximum absorption limit of a freestanding 2D material, can be achieved in (Mo,W)Si2N4/α2‐(Mo,W)Ge2P4 vdWHs. The findings unravel the enormous potential of (Mo,W)Si2N4 vdWHs in designing ultimately compact excitonic solar cell device technology.

Cataloguing MoSi2N4 and WSi2N4 van der Waals Heterostructures: An Exceptional Material Platform for Excitonic Solar Cell Applications


 Building novel van der Waals (vdW) heterostructures is a feasible method to expand material properties and applications. A MoSi2N4/blue phosphorus (BlueP) heterostructure is designed and investigated as a potential photocatalytic candidate by first-principle calculations. Based on the band alignment and electron transfer, MoSi2N4/BlueP exhibits the characteristics of direct Z-scheme vdW heterostructure, which is favorable for the spatial separation of photogenerated carriers and retains a strong redox capacity. Moreover, the MoSi2N4/BlueP possesses suitable band-edge positions for overall water splitting. Compared with the light absorption of two monolayer materials, the heterostructure has a stronger light absorption from the visible to ultraviolet region. The solar to hydrogen conversion efficiency can reach 21.1% for the heterostructure, which is over 3-fold and 4-fold as great as that of pristine MoSi2N4 and BlueP monolayers, respectively. All the results show that the MoSi2N4/BlueP heterostructure is a promising photocatalyst for overall water splitting, and it provides new possibilities for designing high-efficiency photocatalysts.

A direct Z-scheme MoSi2N4/BlueP vdW heterostructure for photocatalytic overall water splitting

Boosting photocatalytic activity through tuning electron spin states and external magnetic fields


 An intrinsic out-of-plane electronic field can inhibit the recombination of photogenerated carriers in two-dimensional (2D) polar materials. On the other hand, a direct Z-scheme constructed from 2D van der Waals heterostructure can not only effectively separate photogenerated carriers, but also can retain robust redox abilities. g-C6N6/InP, a direct Z-scheme heterostructure with a polarized material is successfully designed, which are verified to be available for overall water splitting through first-principles calculations. Due to the synergistic effects of intrinsic electric field and a direct Z-scheme heterostructure, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can simultaneously take place on the g-C6N6 and InP monolayer, respectively. The predicted solar-to-hydrogen (STH) efficiency can reach up to 21.69%, which breaks the conventional theoretical limit of ~18%. The suitable direction of intrinsic electronic field in the polar material can enhance the photogenerated carrier migration and redox abilities for both HER and OER. Based on these findings, the g-C6N6/InP vdW heterostructure can provide a new perspective for finding higher-efficiency Z-scheme photocatalysts with polar materials for overall water decomposition.

A direct Z-scheme g-C6N6/InP van der Waals Heterostructure: A Promising Photocatalyst for High-Efficiency Overall Water Splitting

In Situ Generation of Flower-like and Microspherical Dendrites to Improve Thermoelectric Properties of p-Type Bi0.46Sb1.54Te3

Exploring low-cost, high-efficiency, and stable photocatalysts is still a significant challenge. SrTiO3, one of the appealing photocatalysts, can meet most of the screening criteria except for its efficiency, which is restricted by its poor absorption of visible light and its prompt photogenerated carrier recombination. Recently, a two-dimensional transition metal carbide Ti3C2Tx (2D MXene) has been found to serve as a co-catalyst due to its excellent metallic conductivity, hydrophilic property, large specific surface area, abundance of active sites, and low reaction barrier to hydrogen production. In this work, SrTiO3 nanoparticles are rationally integrated with Ti3C2Tx nanosheets via a simple hydrothermal process. The hydrogen production rate can achieve up to 3.43 mmol g−1 h−1 in the hybridization of SrTiO3-3 wt. % Ti3C2Tx, which is almost six times that of SrTiO3 alone. This remarkable enhancement arises predominantly from the Schottky contact between SrTiO3 and Ti3C2Tx, which can effectively suppress the recombination of photogenerated carriers and accelerate their separation. In addition, such enhancement benefits from the hydrogen evolution capacity of Ti3C2Tx. This work opens an excellent prospect for constructing highly active, low-cost, and stable photocatalysts with 2D MXene and finding potential applications of 2D MXene in energy conversion fields.

Cheng Xiao Peng

Papers

A direct Z-scheme MoSi2N4/BlueP vdW heterostructure for photocatalytic overall water splitting

Boosting photocatalytic activity through tuning electron spin states and external magnetic fields

A direct Z-scheme g-C6N6/InP van der Waals Heterostructure: A Promising Photocatalyst for High-Efficiency Overall Water Splitting

In Situ Generation of Flower-like and Microspherical Dendrites to Improve Thermoelectric Properties of p-Type Bi0.46Sb1.54Te3

SrTiO3/Ti3C2Tx Schottky heterojunction as a promising high-efficiency photocatalyst for H2 evolution