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Photocatalysis has been widely used as one of the most promising approaches to remove various pollutants in liquid or gas phases during the last decade. The main emphasis of the study is on the synergy of vacancy engineering and heterojunction formation, two widely used modifying approaches, to significantly alter photocatalytic performance. The vacancy-induced Ag 2 CO 3 /BiOBr/WO 3-x heterojunction system has been fabricated using a co-precipitation technique to efficiently abate methylene blue (MB) dye and doxycycline (DC) antibiotic. The as-fabricated Ag 2 CO 3 /BiOBr/WO 3-x heterojunction system displayed improved optoelectronic characteristic features because of the rational combination of dual charge transferal route and defect modulation. The Ag 2 CO 3 /BiOBr/WO 3-x system possessed 97% and 74% photodegradation efficacy for MB and DC, respectively, with better charge isolation and migration efficacy. The ternary photocatalyst possessed a multi-fold increase in the reaction rate for both MB and DC, i.e., 0.021 and 0.0078 min−1, respectively, compared to pristine counterparts. Additionally, more insightful deductions about the photodegradation routes were made possible by the structural investigations of MB and DC using density functional theory (DFT) simulations. This study advances the understanding of the mechanisms forming visible light active dual Z-scheme heterojunction for effective environmental remediation. • Vacancy induced Ag 2 CO 3 /BiOBr/WO 3-x was fabricated using co-precipitation method. • O V in WO 3 and dual charge transferal route synergistically boosted the charge isolation efficacy. • •OH, and •O 2 − were the main reactive species responsible for the photodegradation of MB and DC. • The MB and DC degradation pathways are validated by DFT and experimental studies. • 97%, and 74% degradation efficacies were obtained for MB and DC, respectively within 1h 15 min. [ABSTRACT FROM AUTHOR]

A simple, efficient and low energy-consuming process available to generate resultful radicals from PMS for organic pollutants removal had been employed in this study. Slag had been used as the activator for organic pollutants degradation under slag/PMS advanced oxidation process. In this work, effects of slag with or without pretreatment on pollutant removal were studied and radical species generated by slag were measured. Calcination pretreatment is one efficient method to enhance the degradation efficiency significantly. Due to Fe 3 O 4 and Fe 2 O 3 became the dominant phases after calcination, it was about 8.6-flods increasing after comparing the pollutant removal efficiency for different slag/PMS system with calcination pretreatment or not. Organic pollutant neither degraded in PMS system at 25 °C nor being absorbed by slag system for 60 min. On the contrary, up to 90% pollutant concentration reduction achieved in the slag/PMS process. During this process, both •OH and SO 4 •- had been detected once slag and PMS interaction in wastewater. Through the free radicals quenching tests,•OH should be the key free radical in this advanced oxidation process for the organic pollutant removal under this alkaline condition. In general, organic degradation rate was determined by the slag dosage, and the maximum degradation efficiency was mainly controlled by the PMS usage. This work is expected to broaden the high-value reutilization way for industrial solid waste. • A simple and efficient reutilization method was proposed for slag as PMS activator. • Both.•OH and SO4•- could be detected in slag/PMS system. • Calcinated pretreatment enhanced the oxidation capacity and degradation efficiency. • Up to 90% organic pollutants degradation achieved in slag/PMS system. • Iron oxide contributed oxidation performance improvement synergized with alkaline. [ABSTRACT FROM AUTHOR]

Abstract In this study, bismuth-TiO 2 nanotube (Bi-TNT) composites were used for the treatment of industrial wastewater. Bi-TNT were synthesized using two- and one-step anodization methods. The obtained composites were analyzed using X-ray diffraction, field emission scanning electron microscopy, UV–visible diffuse reflectance spectroscopy, Energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. For the two-step Bi-TNT composites, we investigated the effect of different Bi deposition times, Bi concentrations, and Bi deposition voltages on photodegradation efficiency. For the one-step Bi-TNT composites, we investigated the effect of different anodization voltages, anodization times, and Bi concentrations. Initially, the optimal synthesis conditions for two- and one-step Bi-TNT catalysts were identified and then these optimized conditions were used for industrial wastewater treatment that was collected from Banwol Sihwa Industrial Complex Republic of Korea. The Bi-TNT two- and one-step composites showed 2.0 and 2.5 times higher photocatalytic activity, respectively, for industrial wastewater treatment than that of TNT in visible-light. Recycling of Bi-TNT composites showed that the one-step composite method was more efficient and stable than the two-step method because Bi coupling and nanotube formation simultaneously occurred. Highlights • Bi-TNT composites were used for photocatalytic treatment of industrial wastewater. • Bi-TNT catalysts were fabricated using two-step and one-step anodization methods. • Effect of Bi concentration, deposition time, anodization volt & time were evaluated. • One-step Bi-TNT composite was more stable and efficient than two-step method. [ABSTRACT FROM AUTHOR]

Environmental pollution and energy crisis have recently become one of the major global concerns. Insincere discharge of massive amount of organic and inorganic wastes into the aqueous bodies causes serious impact on our environment. However, these organic substances are significant sources of carbon and energy that could be sustainably utilized rather than being discarded. Photocatalytic fuel cell (PFC) is a smart and novel energy conversion device that has the ability to achieve dual benefits: degrading the organic contaminants and simultaneously generating electricity, thereby helping in environmental remediation. This article presents a detailed study of the recent advancements in the development of PFC systems and focuses on the fundamental working principles of PFCs. The degradation of various common organic and inorganic contaminants including dyes and antibiotics with simultaneous power generation and hydrogen evolution has been outlined. The impact of various operational factors on the PFC activity has also been briefly discussed. Moreover, it provides an overview of the design guidelines of the different PFC systems that has been developed recently. It also includes a mention of the materials employed for the construction of the photo electrodes and highlights the major limitations and relevant research scopes that are anticipated to be of interest in the days to come. The review is intended to serve as a handy resource for researchers and budding scientists opting to work in this area of PFC devices. • Summary of the recent advancement of PFCs. • Detailed explanation of the mechanism involved in the photoelectrodes. • Utilization of advanced PFCs for degradation of pollutants simultaneously generating electricity and hydrogen. • Next generation smart technology for treatment of wastewater. • Emerging prospects of smart material based PFCs. [ABSTRACT FROM AUTHOR]

The recent expeditious industrialization and urbanization showcase the increasing need for renewable and non-renewable energy and the severe environmental crisis. In this regard, numerous 2-dimensional (2D) nanomaterials have been developed as a facile approach to meet the futuristic energy essentials and to resolve the crisis. In contrast, the newly explored 2D MXenes (transition metal carbide/nitrides/carbonitride) have been employed as an intriguing material for various environmental applications. This development is accredited to their unique properties, which include a vast surface area, strong electrical conductivity, fascinating photophysical properties, high mechanical properties, stability in an aqueous medium, high hydrophilicity, biocompatibility, ease of functionalization, and excellent thermal properties. MXenes act as a potential candidate in water desalination, energy storage devices such as electrodes of Li-ion batteries and pseudo capacitors, hydrogen production, sensors, and wastewater treatment. This review article deliberates the synthesis of MXene and nanocomposites of MXene and their photo-catalytic actions against various toxic pollutants such as organic dyes and heavy metals in wastewater. This review also precises the various preparation methods of MXene-based photocatalyst and the enhanced photocatalytic activity of MXene and MXene-based nanocomposites in wastewater treatment. Also, it details the attempts made to improve the photocatalytic activity of MXene-based nanocomposites in terms of their structural compositions. In addition, the merits and demerits of the MXene-based photocatalysts are deliberated, which may pave the way for future research in this arena. • This review article deliberates the various preparation methods of MXene based materials. • Photocatalytic activity of MXene based materials were discussed in detail. • Further, attempts were made to improve the photocatalytic activity of MXene based nanocomposites. [ABSTRACT FROM AUTHOR]

The contamination of marine sediments by 4-nonylphenol (4-NP) has become a global environmental problem, therefore there are necessaries searching appropriate and sustainable remediation methods for in-situ applications. Herein, water hyacinth [(WH) (Eichhornia crassipes)]-derived metal-free biochar (WHBC) prepared at 300–900 °C was used to promote the calcium peroxide (CP)-mediated remediation of 4-NP-contaminaed sediments. At [CP] = 4.37 × 10−4 M, [WHBC] = 1.5 g L−1, and pH = 6.0, the degradation of 4-NP was 77% in 12 h following the pseudo-first order rate law with rate constant (k obs) of 4.2 × 10−2 h−1. The efficient 4-NP degradation performance and reaction mechanisms of the WHBC/CP system was ascribed to the synergy between the reactive species (HO• and 1O 2) at the WHBC surface on which there were abundant electron-rich carbonyl groups and defects/vacancies in the catalyst structure provides active sites, and the ability of the graphitized carbon framework to act as a medium for electron shuttling. According to microbial community analysis based on amplicon sequence variants, bacteria of the genus Solirubrobacter (Actinobacteria phylum) were dominant in WHBC/CP-treated sediments and were responsible for the biodegradation of 4-NP. The results showed great promise and novelty of the hydroxyl radical–driven carbon advanced oxidation processes (HR-CAOPs) that relies on the value-added utilization of water hyacinth for contaminated sediment remediation in achieving circular bioeconomy. • 4-Nonylphenol-contaminated sediments were remediated by treatment with biochar/CaO 2. • Combined biochar and CaO 2 exhibited better performance than used separately. • The synergy and effects of treatment on the bacterial community were studied. • Insights into the mechanism of pollutant degradation were provided. • The key genus responsible for 4-nonylphenol biodegradation was Solirubrobacter. [ABSTRACT FROM AUTHOR]

Using solar energy to catalyse photo-driven processes to address the energy crisis and environmental pollution plays a role in the path to a sustainable society. Many oxide-based materials, especially perovskite oxides, have been widely investigated as catalysts for photocatalysis in energy and environment because of the low-cost and earth-abundant and good performance. At this stage, there is a need to present a scientific-based evaluation of the technologies developed so far and identify the most sustainable technologies and the existing limitations and opportunities for their commercialisation. This work comprehensively investigated the outcomes using various scientometric indices on perovskite oxide-based photo(electro)catalysts for water splitting, nitrogen fixation, carbon dioxide conversion, organic pollutant degradation, current trends and advances in the field. According to the results achieved, efforts in both energy and environment based on perovskite oxides have been initiated in the 1990s and accelerated since the 2010s. China and the United States were identified as the most contributing countries. Based on the results achieved in this study, the main milestones and current trends in the development of this field have been identified. The aim of this research is to provide useful guidelines for the further investigation of perovskite oxide-based catalysts for photoelectrocatalysis and photocatalysis both in energy and environment on the applications such as water splitting, nitrogen fixation, carbon dioxide conversion, and wastewater treatment. [ABSTRACT FROM AUTHOR]