A highly ordered honeycomb-like nickel(III/II) oxide-enhanced photocatalytic fuel cell for effective degradation of bisphenol A

Eminent destruction of organics and pathogens concomitant with power generation in a visible light-responsive photocatalytic fuel cell with NiFe2O4/ZnO pine tree-like photoanode and CuO/Cu2O nanorod cathode

Environmental conservation and energy scarcity have become two core challenges with the ever-increasing advancement of industry, particularly chemical energy rich wastewater comprising refractory organics and pathogenic microbes. Here, a multifunctional photocatalytic fuel cell (PFC) was devised using NiFe2O4 nanoparticle-loaded on pine tree-like ZnO/Zn (NiFe2O4/ZnO/Zn) photoanode and CuO/Cu2O nanorods-loaded on Cu (CuO/Cu2O/Cu) cathode for extracting electricity upon wastewater treatment. When fed with Rhodamine B (RhB) dyestuff, the NiFe2O4/ZnO/Zn-PFC provided the maximum power density (Pmax) of 0.539 mW cm-2 upon visible light irradiation with an average RhB degradation of 85.2%, which were 2.8 and 2.7 times higher than ZnO/Zn, respectively. The remarkable enhanced NiFe2O4/ZnO/Zn-PFC performance was owing to the synergistic effect of pine tree-like structure and Z-scheme heterostructure. The pine tree-like with high surface area was not only for effective harnessing photon energies but also provided more directional routes for rapid segregation and transport of carriers and higher interface contacting areas with electrolyte. Through a series of systematic characterizations, the Z-scheme heterostructure mechanism of the system and organics degradation pathway were also speculated. Additionally, the performance of the NiFe2O4/ZnO/Zn-PFC in industry printing wastewater showed Pmax of 0.600 mW cm-2, which was considerably impressive as real wastewater was challenging to accomplish. The phytotoxicity outcome also manifested that the comprehensive toxicity of RhB was eradicated after PFC treatment. Lastly, the excellent recyclability and the pronounced bactericidal effect towards Escherichia coli and Staphylococcus aureus were other attributions which enabled the NiFe2O4/ZnO/Zn-PFC for possible practical application.

Sustainable degradation of pollutants, generation of electricity and hydrogen evolution via photocatalytic fuel cells: An Inclusive Review

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.

Synergy of photocatalysis and fuel cells: A chronological review on efficient designs, potential materials and emerging applications

The rising demand of energy and lack of clean water are two major concerns of modern world. Renewable energy sources are the only way out in order to provide energy in a sustainable manner for the ever-increasing demands of the society. A renewable energy source which can also provide clean water will be of immense interest and that is where Photocatalytic Fuel Cells (PFCs) exactly fit in. PFCs hold the ability to produce electric power with simultaneous photocatalytic degradation of pollutants on exposure to light. Different strategies, including conventional Photoelectrochemical cell design, have been technically upgraded to exploit the advantage of PFCs and to widen their applicability. Parallel to the research on design, researchers have put an immense effort into developing materials/composites for electrodes and their unique properties. The efficient strategies and potential materials have opened up a new horizon of applications for PFCs. Recent research reports reveal this persistently broadening arena which includes hydrogen and hydrogen peroxide generation, carbon dioxide and heavy metal reduction and even sensor applications. The review reported here consolidates all the aspects of various design strategies, materials and applications of PFCs. The review provides an overall understanding of PFC systems, which possess the potential to be a marvellous renewable source of energy with a handful of simultaneous applications. The review is a read to the scientific community and early researchers interested in working on PFC systems.

Facile Synthesis of Sillén-Aurivillius Layered Oxide Bi7Fe2Ti2O17Cl with Efficient Photocatalytic Performance for Degradation of Tetracycline

The development of an efficient and environment-friendly photocatalyst for antibiotics degradation is of great significance and still remains a major challenge. Herein, a novel Sillén-Aurivillius layered oxide Bi7Fe2Ti2O17Cl is successfully synthesized via a one-step flux route (noted as F-BFTOC) and solid-state reaction (noted as S-BFTOC). The as-prepared F-BFTOC manifests the enhanced visible-light photocatalytic performance towards tetracycline (TC) degradation compared with Bi4NbO8Cl and its degradation efficiency reaches 90% within 90 min. Additionally, the proposed degradation pathway and photocatalytic mechanism are systematically investigated by liquid chromatography tandem-mass spectrometry (HPLC-MS), active species trapping test, electron spin resonance (ESR) and first-principles calculations. The superior degradation of antibiotics is primarily derived from the photo-generated h+, and radical ·O2− as the dominant active species. More importantly, the F-BFTOC exhibits excellent cycle stability and TC is ultimately transformed into non-toxic open-loop products. Simultaneously, Rhodamine B (RhB) as a typical organic pollutant is further employed to evaluate the photocatalytic activity of F-BFTOC, and 98% of the degradation efficiency is achieved. BFTOC as a multifunctional photocatalyst for pollutant degradation offers a new insight for Sillén-Aurivillius photocatalytic in the field of water purification.

Direct catalytic decomposition of N2O over bismuth modified NiO catalysts

Direct catalytic decomposition is a promising technology to control the emission of nitrous oxide (N₂O) during fossil fuel combustion and various chemical industries. In this study, a series of NiO catalysts modified with different metal oxides (M_aNiO_b) were prepared by the co-precipitation method and employed for the direct catalytic decomposition of N₂O. Bismuth (Bi) species was confirmed to be the most optimal promoter and the Bi_0.1NiO_1.15 catalyst with a Bi/Ni molar ratio of 0.1 exhibited the best activity over the temperature range of 300-450 °C. The addition of Bi species also promoted the steam resistance capability of the NiO catalyst. Moreover, the physicochemical properties of pure and Bi-modified NiO catalysts were further determined by several characterization methods. The surface areas and capacity of oxygen adsorption/desorption over the catalyst were noticeably improved with the doping of Bi species. Besides, the presence of doped-Bi facilitated the creation of both Ni³⁺ and surface oxygen vacancies on NiO, which promoted the performance of N₂O decomposition. Whereas, the excessive Bi species would accumulate to form large Bi₂O₃ grains, which diminished the surface areas and covered the active sites on the catalysts, leading to the rapid degradation of N₂O catalytic decomposition.

Bi4NbO8Cl {001} nanosheets coupled with g-C3N4 as 2D/2D heterojunction for photocatalytic degradation and CO2 reduction

Photocatalytic activity is largely restricted by insufficient photoabsorption and intense recombination between charge carriers. Here, we first synthesized Bi₄NbO₈Cl nanosheets with {001} exposing facets by a molten-salt growth method, which shows largely promoted photocatalytic performance for the degradation of tetracycline (TC) and bisphenol A (BPA) in comparison with Bi₄NbO₈Cl particles obtained by solid-state reaction. The 2D/2D Bi₄NbO₈Cl/g-C₃N₄ heterojunction photocatalysts were then fabricated via high-energy ball-milling and post-sintering to realize intimate interfacial interaction. The photocatalytic activity of all the Bi₄NbO₈Cl/g-C₃N₄ composites largely enhances compared to Bi₄NbO₈Cl nanosheets and g-C₃N₄, also far exceeding the mechanically-mixed Bi₄NbO₈Cl nanosheets and g-C₃N₄. The impact of different reaction parameters on the photocatalytic degradation activities was investigated, including catalyst concentration, pH value and TC concentration. In addition, Bi₄NbO₈Cl/g-C₃N₄ also presents improved photocatalytic CO₂ reduction activity for CO production. The large enhancement on photocatalytic activity of Bi₄NbO₈Cl/g-C₃N₄ composites is owing to the synergistic effect of favorable 2D/2D structure and construction of type II heterojunction with intimate interfacial interaction, thus boosting the charge separation. The formation of type II heterojunction was evidenced by selective photo-deposition of Pt and MnO_x, which demonstrate that the reductive sites and oxidative sites are on Bi₄NbO₈Cl nanosheets and g-C₃N₄, respectively. This work may provide some insights into fabrication of efficient visible-light driven photocatalysts for environmental and energy applications.

Recent advances on photocatalytic fuel cell for environmental applications-The marriage of photocatalysis and fuel cells

Environmental pollution and energy crisis have become recent worldwide concerns. Huge amounts of organic wastes are discharged into water bodies, causing serious environmental pollution. Meanwhile, these organic compounds are important carbon and energy sources that could be utilized instead of being discarded. A smart design of a photocatalytic fuel cell (PFC) can achieve double benefits: it can degrade organic pollutants and at the same time generate energy. In this review article, we discuss recent progress in the development of PFC systems, and summarize the principles for constructing advanced PFC systems. We particularly focus on the rational design of electrode materials in terms of surface, morphology, facet, and interfacial reaction engineering. The impact of important operational parameters on PFC performance is further discussed in detail. We then discuss the major limitations and opportunities for future PFCs research. The development of smart and advanced PFC systems depends on highly interdisciplinary collaborations, which require concerted efforts from the communities of materials science, chemistry, engineering, and environmental science.

Enhanced Electricity Generation and H2O2 Production in a Photocatalytic Fuel Cell and Fenton Hybrid System Assisted with Reverse Electrodialysis

A novel integrating system coupled with photocatalytic fuel cell and Fenton system assisted by reverse electrodialysis (PREC) is proposed. The results demonstrate that H₂O₂ concentration increased continuously in the reaction process to finally reach 960 mg/L and the current became stable at around 5.2 mA. The salinity-driven potential derived from the high concentration and low concentration cells in the hybrid system was 0.72 and 0.90 V respectively, at the salinity ratio of 50 and 100. The hybrid system has an energy recovery of 16%, a cathodic efficiency of 51%, and the maximum power of 76 W/m² at a salinity ratio of 50, with a 100 Ω external resistance. It is proved that PREC-Fenton possessed great potential in industrial wastewater treatment.