Two-dimensional ultrathin metal-based nanosheets for photocatalytic CO2 conversion to solar fuels

Synergistic sustainability: Future potential of integrating produced water and CO2 for enhanced carbon capture, utilization, and storage (CCUS)

Produced water (PW) and carbon dioxide (CO2) are traditionally considered waste streams the oil and gas industry and other sectors generate. However, these waste products are examples of "waste to wealth" products with a dual nature of being valuable products or disposable byproducts. PW contains various elements and compounds that can be extracted and used in the manufacturing or chemical processing industry. Concentrated brine is generated from PW and can be used as feedstock in chemical processes. On the other hand, excess CO2 produced in various industrial processes needs to be sequestered either through non-conversion processes, such as enhanced oil recovery and storage in geological formations, or through CO2 conversion processes into fuels, polymers, and chemicals. While there is growing interest in reusing these products individually, no studies have explored the opportunities for producing additional chemicals or valuable products by combining CO2 and PW waste streams (CO2-PW). This study identifies the potential resources that can be generated by combining the beneficial reuse of PW and CO2 conversion processes. CO2-PW chemical conversion presents an opportunity to expand the carbon capture, utilization, and storage (CCUS) mix while reducing the environmental impact of disposing of these byproducts. The advantages of utilizing these waste streams for diverse applications are linked with the sustainable management of PW and decarbonization, contributing positively to a more responsible approach to resource management and climate change mitigation.

Interface Engineering in 2D/2D Heterogeneous Photocatalysts

Assembling different 2D nanomaterials into heterostructures with strong interfacial interactions presents a promising approach for novel artificial photocatalytic materials. Chemically implementing the 2D nanomaterials' construction/stacking modes to regulate different interfaces can extend their functionalities and achieve good performance. Herein, based on different fundamental principles and photochemical processes, multiple construction modes (e.g., face-to-face, edge-to-face, interface-to-face, edge-to-edge) are overviewed systematically with emphasis on the relationships between their interfacial characteristics (e.g., point, linear, planar), synthetic strategies (e.g., in situ growth, ex situ assembly), and enhanced applications to achieve precise regulation. Meanwhile, recent efforts for enhancing photocatalytic performances of 2D/2D heterostructures are summarized from the critical factors of enhancing visible light absorption, accelerating charge transfer/separation, and introducing novel active sites. Notably, the crucial roles of surface defects, cocatalysts, and surface modification for photocatalytic performance optimization of 2D/2D heterostructures are also discussed based on the synergistic effect of optimization engineering and heterogeneous interfaces. Finally, perspectives and challenges are proposed to emphasize future opportunities for expanding 2D/2D heterostructures for photocatalysis.

Increasing electron density by surface plasmon resonance for enhanced photocatalytic CO2 reduction

The photocatalytic CO₂ reduction reaction is a multi-electron process, which is greatly affected by the surface electron density. In this work, we synthesize Ag clusters supported on In₂O₃ plasmonic photocatalysts. The Ag-In₂O₃ compounds show remarkedly enhanced photocatalytic activity for CO₂ conversion to CO compared to pristine In₂O₃. In the absence of any co-catalyst or sacrificial agent, the CO evolution rate of optimal Ag-In₂O₃-10 is 1.56 μmol/g/h, achieving 5.38-folds higher than that of In₂O₃ (0.29 μmol/g/h). Experimental verification and DFT calculation demonstrate that electrons transfer from Ag clusters to In₂O₃ on Ag-In₂O₃ compounds. In Ag-In₂O₃ compounds, Ag clusters serving as electron donators owing to the SPR behaviour are not helpful to decline photo-induced charge recomnation rate, but can provide more electron for photocatalytic reaction. Overall, the Ag clusters promote visible-light absorption and accelerate photocatalytic reaction kinetic for In₂O₃, resulting in the photocatalytic activity enhancement of Ag-In₂O₃ compounds. This work puts insight into the function of plasmonic metal on enhancing photocatalysis performance, and provides a feasible strategy to design and fabricate efficient plasmonic photocatalysts.

Potentially toxic elements (PTEs) in Gomti-Ganga Alluvial Plain, associated human health risks assessment and potential remediation using novel-nanomaterials

The health risks associated with consumption of water from river Gomti polluted with potentially toxic elements (PTEs), including As, Fe, Pb, Cd, Mn, Cr, Ni, and Hg were investigated at the initiation of unlocking of COVID-19 lockdown and compared with pre-COVID-19 lockdown status. In the current investigation, the total hazard index (THI) values exceeded the acceptable limit of "unity" at all sampling stations. The use of river water for drinking and domestic purposes by millions of people with high THI values has emerged as a matter of huge concern. The individual hazard quotients associated with Cd and Pb were found to be most severe (> 1). A vivid difference between the THI values during the two study phases indicated the positive impact of COVID-19 lockdown signifying the prominent impact of anthropogenic activities on the PTE concentrations. The closure of local manufacturing units (textile, battery, etc.) emerged as a potential reason for decreased health risks associated with PTE levels. The higher susceptibility of children to health risks in comparison with adults through the values of THI and HQs was interpreted across the study area. Potential remedial measures for PTE contamination have also been suggested in the study.