Study of high active and redox-stable La 0.9 Ca 0.1 Fe 0.9 Nb 0.1 O 3-δ /Sm 0.1 Ce 0.9 O 2−δ composite ceramic electrode for solid oxide reversible cells

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.

Mutual Conversion of CO-CO2 on a Perovskite Fuel Electrode with Endogenous Alloy Nanoparticles for Reversible Solid Oxide Cells

Reversible solid oxide cells (RSOCs) can efficiently render the mutual conversion between electricity and chemicals, for example, electrolyzing CO₂ to CO under a solid oxide electrolysis cell (SOEC) mode and oxidizing CO to CO₂ under a solid oxide fuel cell (SOFC) mode. Nevertheless, the development of RSOCs is still hindered, owing to the lack of catalytically active and carbon-tolerant fuel electrodes. For improving mutual CO-CO₂ conversion kinetics in RSOCs, here, we demonstrate a high-performing and durable fuel electrode consisting of redox-stable Sr₂(Fe, Mo)₂O_6-δ perovskite oxide and epitaxially endogenous NiFe alloy nanoparticles. The electrochemical impedance spectrum (EIS) and distribution of relaxation time (DRT) analyses reveal that surface/interface oxygen exchange kinetics and the CO/CO₂ activation process are both greatly accelerated. The assembled single cell produces a maximum power density (MPD) of 443 mW cm^-2 at 800 °C under the SOFC mode, with the corresponding CO oxidation rate of 5.524 mL min^-1 cm^-2. On the other hand, a current density of -0.877 A cm^-2 is achieved at 1.46 V under the SOEC mode, equivalent to a CO₂ reduction rate of 6.108 mL min cm^-2. Furthermore, reliable reversible conversion of CO-CO₂ is proven with no performance degradation in 20 cycles under SOEC (1.3 V) and SOFC (0.6 V) modes. Therefore, our work provides an alternative way for designing highly active and durable fuel electrodes for RSOC applications.

Progress and prospects of reversible solid oxide fuel cell materials

Reversible solid oxide fuel cell (RSOFC) is an energy device that flexibly interchanges between electrical and chemical energy according to people's life and production needs. The development of cell materials affects the stability and cost of the cell, but also restricts its market-oriented development. After decades of research by scientists, a lot of achievements and progress have been made on RSOFC materials. According to the composition and requirements of each component of RSOFC, this article summarizes the research progress based on materials and discusses the merits and demerits of current cell materials in electrochemical performance. According to the efficiency of different materials in solid oxide fuel cell (SOFC mode) and solid oxide electrolyzer (SOEC mode), the challenges encountered by RSOFC in the operation are evaluated, and the future development of RSOFC materials is boldly prospected.

Excellent Electrochemical Performance of La0.3Sr0.7Fe0.9Ti0.1O3-δ as a Symmetric Electrode for Solid Oxide Cells

Solid oxide cells (SOCs) can switch between fuel cell and electrolysis cell modes, which alleviate environmental and energy problems. In this study, the La_0.3Sr_0.7Fe_0.9Ti_0.1O_3-δ (LSFTi 91) perovskite is innovatively used as a symmetric electrode for solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). LSFTi 91 exhibits a pure perovskite phase in both oxidizing and reducing atmospheres, and the maximum conductivity in air and 5% H₂/Ar is 150 and 1.1 S cm^-1, respectively, which meets the requirement of the symmetric electrode. The polarization resistance (R_p) at 1.5 V is as low as 0.09 Ω cm² in the SOEC mode due to the excellent CO₂ adsorption capacity. The current density can reach 1.9 A cm^-2 at 1.5 V and 800 °C, which is the highest electrolytic performance in the reported single-phase electrodes. LSFTi 91 also exhibits eminent oxygen reduction reaction and hydrogen oxidation reaction (ORR and HOR) activities, with R_p of 0.022 and 0.15 Ω cm² in air and wet H₂, respectively. The peak power density of SOFC could reach 847 mW cm^-2 at 800 °C. In addition, good reversibility is confirmed in the cyclic operation of SOFC and SOEC.

New insights into the degradation of synthetic pollutants in contaminated environments

The environment is contaminated by synthetic contaminants owing to their extensive applications globally. Hence, the removal of synthetic pollutants (SPs) from the environment has received widespread attention. Different remediation technologies have been investigated for their abilities to eliminate SPs from the ecosystem; these include photocatalysis, sonochemical techniques, nanoremediation, and bioremediation. SPs, which can be organic or inorganic, can be degraded by microbial metabolism at contaminated sites. Owing to their diverse metabolisms, microbes can adapt to a wide variety of environments. Several microbial strains have been reported for their bioremediation potential concerning synthetic chemical compounds. The selection of potential strains for large-scale removal of organic pollutants is an important research priority. Additionally, novel microbial consortia have been found to be capable of efficient degradation owing to their combined and co-metabolic activities. Microbial engineering is one of the most prominent and promising techniques for providing new opportunities to develop proficient microorganisms for various biological processes; here, we have targeted the SP-degrading mechanisms of microorganisms. This review provides an in-depth discussion of microbial engineering techniques that are used to enhance the removal of both organic and inorganic pollutants from different contaminated environments and under different conditions. The degradation of these pollutants is investigated using abiotic and biotic approaches; interestingly, biotic approaches based on microbial methods are preferable owing to their high potential for pollutant removal and cost-effectiveness.

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.

Cu-Doped Sr2Fe1.5Mo0.5O6−δ as a highly active cathode for solid oxide electrolytic cells

Perovskite oxide Sr₂Fe_1.3Cu_0.2Mo_0.5O_6−δ (SFCM) is prepared and evaluated as a novel cathode material for solid oxide electrolytic cells (SOECs).