Highly stable and durable ZnIn2S4 nanosheets wrapped oxygen deficient blue TiO2(B) catalyst for selective CO2 photoreduction into CO and CH4.

Developing new and highly stable efficient photocatalysts is crucial for achieving high performance and selective photocatalytic CO2 conversion. In this paper, we designed a one-dimensional oxygen-deficient blue TiO2(B) (BT) catalyst for improved electron mobility and visible light accessibility. In addition, hexagonal ZnIn2S4 (ZIS) nanosheets with a low bandgap and great visible light accessibility are employed to produce effective heterostructures with BT. The synthesized materials are tested for photocatalytic conversion of CO2 into solar fuels (H2, CO and CH4). The optimized composite yields 71.6 and 10.3 µmol g-1h-1 of CO and CH4, three and ten times greater than ZIS, respectively. When ZIS nanosheets are combined with a one-dimensional oxygen-deficient BT catalyst, improved electron mobility and visible light accessibility are achieved, charge carriers are effectively segregated, and the transfer process is accelerated, resulting in efficient CO2 reduction. The photocatalytic CO2 conversion activity of the constructed BT/ZIS heterostructures is very stable over a 10-day (240-hour) period, and CO and CH4 production rates increase linearly with time; however, as time goes on, the rates of H2 production decrease. Further, a five-time recycling test confirmed this, revealing essentially equal activity and selectivity throughout the experiment. As a result, CO2 to CO and CH4 conversion has high selectivity and longer durability. The band structure of the BT/ZIS composite is determined using Mott-Schottky measurement, diffuse reflectance spectroscopy, and valence band X-ray photoelectron spectroscopy. This research demonstrates a novel approach to investigating effective, stable, and selective photocatalytic CO2 reduction systems for solar-to-chemical energy conversion.

Impact of the number of surface-attached tungsten diselenide layers on cadmium sulfide nanorods on the charge transfer and photocatalytic hydrogen evolution rate.

The selection of layered number and time-course destruction of layers may affect the charge transfer between 2D-to-1D heterostructure, making it possible to improve the efficiency of solar-to-hydrogen evolution. Herein, we demonstrate a simple, low-cost systematic protocol of 2D-WSe2 nanolayer numbers ranging from 7 to 60 aiding the ultrasonication time-course. The resultant nanolayers were assembled on the surface of 1D-CdS nanorods, which demonstrated an improved surface shuttling property. Consequently, a drastic improvement in photocatalytic solar-driven hydrogen evolution was observed (103.5 mmol h-1 g-1) with seven-layered WSe2 (few-layered WSe2) attached on CdS nanorods surface. This enhanced photocatalytic performance is attributed to the selection of layers on CdS surface that expose abundant active sites; along with suitable energy levels, this can facilitate increased charge transfer leading to feasible photocatalytic reactions. Significantly, the present study proposes an efficient and sustainable process to produce hydrogen and demonstrates the potential of numbered WSe2 nanosheets as a co-catalyst material.

Tuning Band Alignments and Charge-Transport Properties through MoSe2 Bridging between MoS2 and Cadmium Sulfide for Enhanced Hydrogen Production.

Transition-metal dichalcogenide materials play a major role in the state-of-the-art innovations for energy conversion because of potential applications resulting from their unique properties. These materials additionally show inordinate potential toward the progress of hygienic power sources to deal with increasing environmental disputes at the time of skyrocketing energy demands. Herein, we report earth-abundant, few-layered, MoSe2-bridged MoS2/cadmium sulfide (CdS) nanocomposites, which reduce photogenerated electron and hole recombination by effectively separating charge carriers to achieve a high photocatalytic efficiency. Accordingly, the MoSe2-bridged MoS2/CdS system produced effective hydrogen (193 µmol·h-1) as that of water using lactic acid as a hole scavenger with the irradiation of solar light. The presence of few-layered MoSe2 bridges in MoS2/CdS successfully separates photogenerated charge carriers, thereby enhancing the shuttling of electrons on the surface to active edge sites. To the best of our knowledge, this few-layered MoSe2-bridged MoS2/CdS system exhibits the most effective concert among altogether-reported MoS2-based CdS composites. Notably, these findings with ample prospective for the development of enormously real photocatalytic systems are due to their economically viable and extraordinary efficiency.

Designing CdS Mesoporous Networks on Co-C@Co9 S8 Double-Shelled Nanocages as Redox-Mediator-Free Z-Scheme Photocatalyst.

Designing porous nanostructures with unprecedented functionalities and an effective ability to harvest the maximum energy region of the solar spectrum and suppress the charge-carrier recombination rate offers promising potential for sustainable energy production. Although several functional porous nanostructures have been developed, high-efficiency materials are still needed. Herein, we report a new, highly active, noble-metal-free, and redox-mediator-free Z-scheme photocatalyst, CdS/Co-C@Co9 S8 , for H2 production through water splitting under solar irradiation. The designed photocatalytic system contains open 3 D CdS mesopores as a light absorber for wider solar-light harvesting. Metal-organicframework-derived cobalt nanocrystal-embedded few-layered carbon@Co9 S8 double-shelled nanocages were used as a co-semiconductor to hamper the photo charge-carrier recombination by accelerating the photogenerated electrons and holes from the other semiconductor. The optimized catalyst shows a H2 evolution rate of 26.69 mmol g-1 h-1 under simulated solar irradiation, which is 46 times higher than that of the as-synthesized CdS mesoporous nanostructures. The apparent quantum yield reached 7.82 % at λ=425 nm in 5 h. The outstanding photocatalytic activity of CdS/Co-C@Co9S8 reflects the favorable suppression of the charge-carrier recombination rate, as determined by photoluminescence, photocurrent, and impedance analyses. We believe that the findings reported here may inspire the design of new noble-metal-free porous nanohybrids for sustainable H2 production.

Light induced aggregation of specific single walled carbon nanotubes.

We report optically induced aggregation and consequent separation of specific diameters of nanotubes from stable solutions of pristine single walled carbon nanotubes (SWNTs). Dispersed solutions of pristine SWNTs in different solvents show rapid and selective aggregation. The separated SWNTs show enrichment in specific diameters of SWNTs aggregating under UV, visible and NIR illumination.