Global warming, environmental pollution, and an energy shortage in the current fossil fuel society may cause a severe ecological crisis. Storage and conversion of renewable, dispersive and ...non-perennial energy from the sun, wind, geothermal sources, water, or biomass could be a promising option to relieve this crisis. Carbon materials could be the most versatile platform materials applied in the field of modern energy storage and conversion. Conventional carbon materials produced from coal and petrochemical products are usually energy intensive or involve harsh synthetic conditions. It is highly desired to develop effective methods to produce carbon materials from renewable resources that have high performance and limited environmental impacts. In this regard, biochar, a bio-carbon with abundant surface functional groups and easily tuned porosity produced from biomass, may be a promising candidate as a sustainable carbon material. Recent studies have demonstrated that biochar-based materials show great application potential in energy storage and conversion because of their easily tuned surface chemistry and porosity. In this review, recent advances in the applications of biochar-based materials in various energy storage and conversion fields, including hydrogen storage and production, oxygen electrocatalysts, emerging fuel cell technology, supercapacitors, and lithium/sodium ion batteries, are summarized, highlighting the mechanisms and open questions in current energy applications. Finally, contemporary challenges and perspectives on how biochar-based materials will develop and, in particular, the fields in which the use of biochar-based materials could be expanded are discussed throughout the review. This review demonstrates significant potential for energy applications of biochar-based materials, and it is expected to inspire new discoveries to promote practical applications of biochar-based materials in more energy storage and conversion fields.
Biochar, a bio-carbon with abundant surface functional groups and easily tuned porosity produced from biomass, shows great application potential in energy storage and conversion. In this review, recent advances in the applications of biochar-based materials in various energy storage and conversion fields are summarized, highlighting the mechanisms and open questions in current energy applications.
A look at how biochar is formed in the biomass pyrolysis process is offered. Research points toward a biochear-based sustainable platform carbon material.
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IJS, KILJ, NUK, PNG, UL, UM
Iron-assisted biological wastewater treatment processes have shown a promising potential in removing various types of contaminants. Synergistic effects between iron and microbes on the contaminant ...degradation make the role of iron beyond that of a nutritional necessity. Exploration of the synergistic mechanisms and the interactions between iron species and microbes and their metabolic products in bio‑iron systems is therefore of significant importance. Iron, including zero-valent iron, ferrous/ferric ions and iron minerals are all reported to be capable of enhancing specific contaminant removals. Although the main role of different iron species in stimulating biological process may differ between each other, their similar transformation pathways may bring us useful information about bio‑iron systems. In this paper, an overview of iron-assisted biological wastewater treatments, including anaerobic digestion, S and Cl reduction, N and P removal, heavy metal immobilization, aromatic and halogenated hydrocarbon compounds degradation, and sludge granulation is provided. Also, the potential synergistic effects between iron and microbes involved in these processes are explored. Furthermore, the main advantages, limitations, and challenges for the development of iron-assisted treatment processes are envisaged.
•Iron-assisted biological wastewater treatment processes are summarized.•Synergistic effects between iron and microbes in bio‑iron systems are highlighted.•Mechanisms behind the iron-enhanced bio-treatment are described.•Concerns on the full-scale application of iron-assisted bio-treatment are discussed.•Potential developments beyond iron-assisted bio-treatment are envisaged.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The electrochemical oxygen evolution reaction (OER) is a core electrode reaction for the renewable production of high‐purity hydrogen, carbon‐based fuel, synthetic ammonia, etc. However, the sluggish ...kinetics of the OER result in a high overpotential and limit the widespread application of OER‐based technologies. Recent studies have shown that bimetallic‐based materials with the synergism of different metal components to regulate the adsorption and dissociation energy of intermediates are promising OER electrocatalyst candidates with a lower cost and energy consumption. In the past two decades, tremendous efforts have been devoted to developing OER applications of bimetallic‐based materials with a focus on compositions, phase, structure, etc., to highlight the synergism of different metal components. However, there is a lack of critical thinking and organized analysis of OER applications with bimetallic‐based materials. This review critically discusses the challenges of developing bimetallic‐based OER materials, summarizes the current optimization strategies to enhance both activity and stability, and highlights the state‐of‐the‐art electrocatalysts for OER. The relationship between the componential/structural features of bimetallic‐based materials and their electrocatalytic properties is presented to form comprehensive electronic and geometric modifications based on thorough analysis of the reported works and discuss future efforts to realize sustainable bimetallic‐based OER applications.
The impressive progress in the rational design of bimetals and bimetallic compounds toward oxygen evolution reaction (OER) is summarized. Based on the main advantages and challenges for the bimetallic‐based OER electrocatalysts, the optimization strategies are presented to modify the electronic structure and geometric construction to highlight the synergism characteristics, including compositional regulation, elemental doping, coordination adjustment, interfacial structure establishment, morphology control, and support interaction for achieving efficient OER performance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The occurrence of microplastics (MPs) as emerging contaminants in the environment may cause changes in water or sediment characteristics, and further affect their biogeochemical cycles. Thus, ...insights into the interactions between dissolved organic matter (DOM) and MPs are essential for the assessment of environmental impacts of MPs in ecosystems. Integrating spectroscopic methods with chemometric analyses, this work explored the chemical and microstructural changes of DOM-MP complex to reveal the mechanism of DOM-MP interaction at a molecular level. MPs were found to interact with the aromatic structure of DOM via π-π conjugation, then be entrapped in the DOM polymers by the carboxyl groups and C=O bonds, constituting a highly conjugated co-polymer with increased electron density. This induced the fluorescence intensity increase in DOM. The interaction affinity of DOM-MP was highly dependent on the MP size and solution pH. This work offers a new insight into the impact of MP discharge on environment and may provide an analytical framework for evaluating MP hetero-aggregation and the roles of MPs in the transportation of other contaminants. Furthermore, the integrated methods used in this work exhibit potential applications in exploring the fragmentation processes of MPs and formation of secondary MPs under natural conditions.
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•DOM is adhered onto MPs via π-π conjugation, carboxyl groups and C=O bonds.•MP-DOM constitutes a conjugated co-polymer with an elevated electron density.•Interaction between DOM and MP depends on MP size and solution pH.•The approach has a great potential in elucidating plastics fragmentation and secondary MPs formation.
The interaction mechanism between humic acid and polystyrene microplastics is explored and new insights into the impact of MP discharge on environment are provided.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Microbial fuel cells (MFCs) have been conceived and intensively studied as a promising technology to achieve sustainable wastewater treatment. However, doubts and debates arose in recent years ...regarding the technical and economic viability of this technology on a larger scale and in a real-world applications. Hence, it is time to think about and examine how to recalibrate this technology's role in a future paradigm of sustainable wastewater treatment. In the past years, many good ideas/approaches have been proposed and investigated for MFC application, but information is scattered. Various review papers were published on MFC configuration, substrates, electrode materials, separators and microbiology but there is lack of critical thinking and systematic analysis of MFC application niche in wastewater treatment. To systematically formulate a strategy of (potentially) practical MFC application and provide information to guide MFC development, this perspective has critically examined and discussed the problems and challenges for developing MFC technology, and identified a possible application niche whereby MFCs can be rationally incorporated into the treatment process. We propose integration of MFCs with other treatment technologies to form an MFC-centered treatment scheme based on thoroughly analyzing the challenges and opportunities, and discuss future efforts to be made for realizing sustainable wastewater treatment.
Microbial fuel cells (MFCs) have been conceived and intensively studied as a promising technology to achieve sustainable wastewater treatment.
Dissolved organic matter (DOM) exists ubiquitously in environments and plays critical roles in pollutant mitigation, transformation, and organic geochemical cycling. Understanding its properties and ...environmental behaviors is critically important to develop water treatment processes and environmental remediation strategies. Generalized two-dimensional correlation spectroscopy (2DCOS), which has numerous advantages, including enhancing spectral resolution and discerning specific order of structural change under an external perturbation, could be used as a powerful tool to interpret a wide range of spectroscopic signatures relating to DOM. A suite of spectroscopic signatures, such as UV–vis, fluorescence, infrared, and Raman spectra that can be analyzed by 2DCOS, is able to provide additional structural information hiding behind the conventional one-dimensional spectra. In this article, the most recent advances in 2DCOS applications for analyzing DOM-related environmental processes are reviewed, and the state-of-the-art novel spectroscopic techniques in 2DCOS are highlighted. Furthermore, the main limitations and requirements of current approaches for exploring DOM-related environmental processes and how these limitations and drawbacks can be addressed are explored. Finally, suggestions and new approaches are proposed to significantly advance the development of 2DCOS in analyzing the properties and behaviors of DOM in natural and engineered environments.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
Glucose electrolysis offers a prospect of value-added glucaric acid synthesis and energy-saving hydrogen production from the biomass-based platform molecules. Here we report that ...nanostructured NiFe oxide (NiFeO
x
) and nitride (NiFeN
x
) catalysts, synthesized from NiFe layered double hydroxide nanosheet arrays on three-dimensional Ni foams, demonstrate a high activity and selectivity towards anodic glucose oxidation. The electrolytic cell assembled with these two catalysts can deliver 100 mA cm
−2
at 1.39 V. A faradaic efficiency of 87% and glucaric acid yield of 83% are obtained from the glucose electrolysis, which takes place via a guluronic acid pathway evidenced by in-situ infrared spectroscopy. A rigorous process model combined with a techno-economic analysis shows that the electrochemical reduction of glucose produces glucaric acid at a 54% lower cost than the current chemical approach. This work suggests that glucose electrolysis is an energy-saving and cost-effective approach for H
2
production and biomass valorization.
Lignin valorization is considered an important part of the modern biorefinery scheme. The unique structure and composition of lignin may offer many effective routes to produce several bulk chemicals ...and functional materials. Thermochemical conversion of lignin to synthesize value-added functional materials has recently attracted a lot of attention. In this review, we have presented currently available approaches and strategies for the thermochemical conversion of lignin to functional carbon materials. The transformation behavior and mechanism of lignin during the thermochemical process (
e.g.
, pyrolysis and hydrothermal carbonization) are illuminated. The characteristics (structure and surface chemistry) of lignin-based functional carbon materials are summarized systematically. The advances in the functionalization of lignin-based carbon materials (surface functionality tuning and porosity tailoring) and the applications of lignin-based functional carbon materials in the fields of catalysis, energy storage, and pollutant removal are reviewed. Perspectives on how lignin-based functional materials would develop and, especially, in which fields the use of these functionalized materials could be expanded are discussed. This review clearly shows that a rational design of the functionalized lignin-based materials will lead to a rich family of hybrid functional carbon materials with various applications toward a green and sustainable future.
The naturally abundant lignin offers a sustainable platform for the synthesis of functional carbon materials which have been widely used in catalysis, energy storage, and pollutant removal.
Peroxymonosulfate (PMS) is extensively used as an oxidant to develop the sulfate radical-based advanced oxidation processes in the decontamination of organic pollutants and various PMS activation ...methods have been explored. Visible-light-assisted PMS activation to construct a Fenton-like process has shown a great potential for pollution control. In our work, BiVO4 nanosheets were prepared using a hydrothermal process and used to activate PMS under visible light. A rapid degradation of ciprofloxacin (CIP) was achieved by dosing PMS (0.96 g/L), BiVO4 (0.32 g/L) under visible light with a reaction rate constant of 77.72-fold higher than that in the BiVO4/visible light process. The electron spin resonance and free radical quenching experiments indicate that reactive species of •O2−, h+, •OH and SO4•− all worked, where h+, •OH and SO4•− were found as the dominant contributors to the CIP degradation. The spectroscopic analyses further demonstrate that the photoinduced electrons were directly involved in the PMS activation process. The generated •O2− was partially utilized to activate PMS and more •OH was produced because of the chain reactions between SO4•− and H2O/OH−. In this process, PMS acted as an electron acceptor to transfer the photo-induced charges from the conduction band of BiVO4 and PMS was successfully activated to yield the high-powered oxidative species. From the degradation intermediates of CIP detected by a liquid-chromatography-mass spectrometer, the possible degradation pathways were proposed. The substantially decreased toxicity of CIP after the reaction was also observed. This work might provide new insights into the visible-light-assisted PMS activation mechanisms and is useful to construct environmentally-friendly catalytic processes for the efficient degradation of organic pollutants.
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•PMS was effectively activated by BiVO4 nanosheets for water purification under visible light.•Separation of electron/hole pairs and generation of oxidative species were enhanced.•Visible-light-assisted PMS activation Fenton-like mechanism was elucidated.•High mineralization and low biotoxicity validated the application potential of the system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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