Ultra-low content of Pt modified CdS nanorods: Preparation, characterization, and application for photocatalytic selective oxidation of aromatic alcohols and reduction of nitroarenes in one reaction system

Selectively Permeable FeOOH Amorphous Layer Coating CdS for Enhancing Photocatalytic Conversion of Benzyl Alcohol and Selectivity to Benzaldehyde

The development of new strategies to improve reaction efficiency and light utilization is one of the biggest challenges in photosynthetic chemistry. Dynamics control, particularly tuning the adsorption/desorption of reactants and products, is an ideal way to improve the conversion and selectivity in catalytic reactions, but it is rarely studied for photocatalytic organic synthesis. This study concerns the design of an amorphous FeOOH coating to decorate CdS photocatalyst to control the adsorption and desorption of reactants and products to improve reaction efficiency for the photocatalytic conversion of benzyl alcohol (BA) into benzaldehyde (BAD). The best conversion of the core-shell photocatalyst is 74.1 % in 2 h, together with >99.9 % selectivity to BAD, and the photocatalyst exhibits response above 600 nm, which is the longest active wavelength reported for the reaction. Further data illustrate that the amorphous FeOOH coating enables selective sorption of BA/BAD molecules by H-bonding interactions, which may result in the excellent performance. Construction of amorphous coating layers and understanding the selective permeability may provide a new strategy for the design of more efficient photocatalytic systems for organic synthesis.

Fast and selective reduction of nitroarenes under visible light with an earth-abundant plasmonic photocatalyst

Reduction of nitroaromatics to the corresponding amines is a key process in the fine and bulk chemicals industry to produce polymers, pharmaceuticals, agrochemicals and dyes. However, their effective and selective reduction requires high temperatures and pressurized hydrogen and involves noble metal-based catalysts. Here we report on an earth-abundant, plasmonic nano-photocatalyst, with an excellent reaction rate towards the selective hydrogenation of nitroaromatics. With solar light as the only energy input, the chalcopyrite catalyst operates through the combined action of hot holes and photothermal effects. Ultrafast laser transient absorption and light-induced electron paramagnetic resonance spectroscopies have unveiled the energy matching of the hot holes in the valence band of the catalyst with the frontier orbitals of the hydrogen and electron donor, via a transient coordination intermediate. Consequently, the reusable and sustainable copper-iron-sulfide (CuFeS₂) catalyst delivers previously unattainable turnover frequencies, even in large-scale reactions, while the cost-normalized production rate stands an order of magnitude above the state of the art.

Review of MXene-based nanocomposites for photocatalysis

Since multilayered MXenes (Ti₃C₂T_x, a new family of two-dimensional materials) were initially introduced by researchers at Drexel University in 2011, various MXene-based nanocomposites have received increased attention as photocatalysts owing to their exceptional properties (e.g., rich surface chemistry, adjustable bandgap structures, high electrical conductivity, hydrophilicity, thermal stability, and large specific surface area). Therefore, we present a comprehensive review of recent studies on fabrication methods for MXene-based photocatalysts and photocatalytic performance for contaminant degradation, CO₂ reduction, H₂ evolution, and N₂ fixation with various MXene-based nanocomposites. In addition, this review briefly discusses the stability of MXene-based nanophotocatalysts, current limitations, and future research needs, along with the various corresponding challenges, in an effort to reveal the unique properties of MXene-based nanocomposites.

Construction of Bi2MoO6/CdS heterostructures with enhanced visible light photocatalytic activity for fuel denitrification

In this work, a novel step-scheme (S-scheme) Bi₂MoO₆/CdS heterojunction (HJ) photocatalyst (PC) was successfully prepared by a two-step solvothermal method for the first time. One-dimensional CdS nanorods were prepared by a simple solvothermal method as a synthesis template. Then, a Bi₂MoO₆ precursor was added to obtain a series of Bi₂MoO₆/CdS HJ composite catalytic materials with different morphologies. The photocatalytic performance of the catalyst was investigated by simulating fuel denitration as a probe reaction under visible light excitation (>420 nm). When compared with pure Bi₂MoO₆ and CdS, the 0.65-Bi₂MoO₆/CdS composite shows the highest photocatalytic activity for pyridine degradation. Degradation of pyridine reached 81% after 240 min of visible light excitation. The degradation rate of 0.65-Bi₂MoO₆/CdS reached 0.4471 h^-1, which was 1.8 and 3.2 times higher than that of CdS (0.2493 h^-1) and Bi₂MoO₆ (0.1427 h^-1), respectively. Combined with a series of characterisation results, the improvement in pyridine degradation activity was mainly attributed to (1) the S-scheme HJ structure between Bi₂MoO₆ and CdS, which greatly promoted the separation of photogenerated electrons and holes while retaining its strong redox ability, (2) the large specific surface area, which provided abundant active sites and efficient adsorption performance and catalytic performance, and (3) the special morphology, which induced multiple reflections of light, thereby improving absorption and utilisation of light. Moreover, after four cycles of pyridine denitrification, the samples still exhibited high activity, indicating good stability and recyclability of the composite catalyst. These findings provide a basis for the development of composite PCs for efficient fuel denitration under visible light irradiation.

Simultaneous Gd2O3 clusters decoration and O-doping of g-C3N4 by solvothermal-polycondensation method for reinforced photocatalytic activity towards sulfamerazine

To improve the visible-light photocatalytic activity of graphitic carbon nitrate (g-C₃N₄) for practical application, a Gd₂O₃-cluster decorated O-doping g-C₃N₄ was fabricated via an ethanol assisted solvothermal-polycondensation method. The as-prepared photocatalysts, including bulk g-C₃N₄ (CN), O-doping g-C₃N₄ (HECN) and Gd₂O₃-cluster decorated O-doping g-C₃N₄ (HECN-xGd), were characterized and the paralleled experiments were conducted to evaluate the photocatalytic activity, mineralization capacity and mineralization mechanism, where sulfamerazine (SMR) was employed as the target pollutant. Furthermore, the quenching tests with scavengers were executed to analyze the contributions of the dominant active species, where the O₂^- was identified as a major role, and h⁺ as the minor role in the photodegradation of SMR. Results from the paralleled experiments suggested that the HECN-xGd possesses superior photocatalytic activity to HECN and CN, besides the feasible reusability through five cycles and impressive total organic carbon (TOC) removal about 60%. And the improved photocatalytic activity of HECN-xGd is ascribed mainly to the oxygen doping and Gd₂O₃ decoration. Herein, oxygen doping optimizes the structure of g-C₃N₄ and expands the light absorption range of HECN, and Gd₂O₃ facilitates the reduction of O₂ into O₂^-, and acts as the separator and transporter for the photo-induced charges.

Selective photocatalytic oxidation of aromatic alcohols to aldehydes with air by magnetic WO3ZnO/Fe3O4. In situ photochemical synthesis of 2-substituted benzimidazoles

Recently, visible light-driven organic photochemical synthesis has been a pioneering field of interest from academic and industrial associations due to its unique features of green and sustainable chemistry. Herein, WO3ZnO/Fe3O4 was synthesized, characterized, and used as an efficient magnetic photocatalyst in the preparation of a range of 2-substituted benzimidazoles via the condensation of benzyl alcohol and o-phenylenediamine in ethanol at room temperature for the first time. The key feature of this work is focused on the in situ photocatalytic oxidation of benzyl alcohols to benzaldehydes under atmospheric air and in the absence of any further oxidant. This new heterogeneous nanophotocatalyst was characterized via XRD, FT-IR, VSM and SEM. Short reaction time, cost-effectiveness, broad substrate scope, easy work-up by an external magnet, and excellent product yield are the major advantages of the present methodology. A number of effective experimental parameters were also fully investigated to clear broadness and generality of the protocol.