Levulinic acid is a sustainable platform molecule that can be upgraded to valuable chemicals and fuel additives. This article focuses on the catalytic upgrading of levulinic acid into various ...chemicals such as levulinate esters, δ‐aminolevulinic acid, succinic acid, diphenolic acid, γ‐valerolactone, and γ‐valerolactone derivatives such valeric esters, 5‐nonanone, α‐methylene‐γ valerolactone, and other various molecular‐weight alkanes (C9 and C18–C27 olefins).
Refined and ready: Lignocellulosic biomass upgrade through the use of levulinic acid offers a wide array of products with a variety of applications ranging from fuel additives to biobased chemicals, green solvents, biopolymers, and biofertilizers.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Over the past 20 years, a revolution has been seen in battery research culminating with a much‐awaited Nobel Prize in Chemistry in 2019 for the development of Li‐ion batteries. New Li‐ion battery ...materials have been developed recently with improvements in performance. New Li battery chemistries have also emerged, exhibiting high energy density such as Li‐S, Li‐O2, Li‐metal with solid state electrolytes as well as zero‐excess Li anode metal batteries. This is tremendous progress and batteries are becoming more efficient and cheaper each year. Yet, most research in batteries is entirely focused on performance while the sustainability of all battery components making up the cell, as well as the battery chemistry itself are much overlooked. In this essay some perspectives are discussed and opinion is provided on the advancement of sustainability in battery research.
Relying solely on lithium‐based battery technologies and on “freshly” mined lithium is unlikely to sustain the “battery revolution” needed to bring about a zero emissions path by 2050. This essay provides some perspectives and research directions needed to improve the future sustainability of batteries.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sodium‐ion batteries (SIBs) have attracted more and more attention for scalable electrical energy storage due to the abundance and wide distribution of Na resources. However, the anode still remains ...a great challenge for the application of SIBs. Here the production of uniform hard carbon microtubes (HCTs) made from natural cotton through one simple carbonization process and their application as an anode are reported. The study shows that the electrochemical performance of the HCTs is seriously affected by the carbonization temperature due to the difference in their microstructure and heteroatomic content. The HCTs carbonized at 1300 °C deliver the highest reversible capacity of 315 mAh g−1 and good rate capability due to their unique tubular structure. This contribution not only provides a new approach for the preparation of hard carbon materials with unique tubular microstructure using natural inspiration, but it also deepens the fundamental understanding of the sodium storage mechanism.
A novel hard carbon material with microtube structure constructed from hollow fiber structure of cotton fiber by simple one‐step carbonization approach is presented. The electrochemical sodium storage difference of hard carbon microtubes with different carbonization temperature and the sodium storage mechanism are systematically investigated in this work.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Nanocarbons are of progressively increasing importance in energy electrocatalysis, including oxygen reduction, oxygen evolution, hydrogen evolution, CO2 reduction, etc. Precious-metal-free or ...metal-free nanocarbon-based electrocatalysts have been revealed to potentially have effective activity and remarkable durability, which is promising to replace precious metals in some important energy technologies,such as fuel cells, metal–air batteries, and water splitting. In this review, rather than overviewing recent progress completely, we aim to give an in-depth digestion of present achievements, focusing on the different roles of nanocarbons and material design principles. The multifunctionalities of nanocarbon substrates（accelerating the electron and mass transport, regulating the incorporation of active components,manipulating electron structures, generating confinement effects, assembly into 3 D free-standing electrodes） and the intrinsic activity of nanocarbon catalysts（multi-heteroatom doping, hierarchical structure,topological defects） are discussed systematically, with perspectives on the further research in this rising research field. This review is inspiring for more insights and methodical research in mechanism understanding, material design, and device optimization, leading to a targeted and high-efficiency development of energy electrocatalysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The aqueous oxygen reduction reaction (ORR) has recently received increased attention due to its critical role in clean and sustainable energy‐generation technologies, such as proton exchange ...membranes (PEM) fuel cells, alkaline fuel cells and Zn–air batteries. The sluggish kinetics associated with ORR result from multistep electron‐transfer process. The slow kinetics are partially related to the O2 adsorption process onto the catalyst, which happens at the triple‐phase boundary (TPB) of the electrocatalyst–electrolyte–oxygen interface. Hence, tremendous efforts have been devoted to improving the intrinsic properties of electrocatalysts such as active sites, electrical conductivity and porosity. Engineering the electrocatalyst's interfacial properties is another critical issue in ORR, however less described in the literature. The surface of the catalyst provides the microenvironment for the triple boundary interface reaction, which directly influences its electrocatalytic activity and the kinetics. This Minireview is a summary of the existing literature on manipulating the interfacial surface of non‐precious metal catalysts at the triple point between the solid catalyst, the aqueous electrolyte and the O2 gas with the aim of improving the ORR efficiency. Various approaches towards improving the wettability and nanostructuring the catalyst surface to boost the activity of the surface‐active sites and provide improved stability are discussed.
Promoting adsorption: The sluggish kinetics resulting from multistep electron transfer processes is the main concern in ORR. Promoting O2 adsorption, which happens on the triple‐phase boundary (TPB) of electrocatalyst–electrolyte–oxygen interface can overcome the slow kinetics. In this paper we review some of the existing surface engineering strategies in the literature aiming to manipulate the triple point boundary (TPB) to promote the aqueous ORR.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A deeper understanding of the water‐splitting hydrogen evolution reaction (HER) mechanism during photocatalytic processes is crucial for the rational design of efficient photocatalysts. In ...particular, the HER mechanism promoted by multielement hybrid structures remains extremely challenging and elusive. Herein, an in situ photoelectrochemical/Raman measurement system is employed to monitor the HER mechanism of hybrid nanostructures under realistic working conditions via operando Raman spectra and linear‐sweep voltammetry curves. As a proof of concept, tunable composition transition metal dichalcogenides MoS2xSe2(1−x) nanosheets are used as a model photocatalyst to unveil the corresponding photocatalytic mechanism. The spectroscopic studies reveal that hydrogen atoms can be adsorbed to active sulfur and selenium atoms via intermediate species formed during the photocatalytic process. More importantly, the studies demonstrate that an exponential relationship exists between the number of reactive electrons and the Raman intensity of intermediate species, which can serve as a guideline to directly evaluate the HER performance in photocatalysts by comparing the Raman intensities of the intermediate species. As a simple, intuitive, and general analytical method, the designed operando Raman measurement approach provides a new tool for elucidating catalytic reaction mechanisms in a realistic and complex environment; and strategically improving H2 production performance of multielement photocatalysts.
A photoelectrochemical‐operando Raman spectroscopy system is employed to reveal the photocatalytic hydrogen evolution reaction intermediates under practical reaction conditions. An exponential function relationship between the quantity of reactive electrons and the Raman intensity of intermediate species is established, which can serve as a guideline to directly evaluate the catalytic performance, and strategically improve hydrogen production performance of multielement photocatalysts.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) are prospective candidates for large‐scale energy storage systems cause of their abundant resources. However, unsatisfactory rate and ...cycling performance of carbon‐based anodes present a bottleneck for the applications of SIBs/PIBs due to the large sizes of sodium/potassium ions. Herein, oxygen‐doped vertically aligned carbon aerogels (VCAs) with hierarchically tailored channels are synthesized as anodes in SIBs/PIBs via a controllable unidirectional ice‐templating technique. VCA‐3 (cooling rate of 3 K min−1) delivers the highest reversible capacity of ≈298 mAh g−1 at 0.1 C with an excellent cycling performance over 2000 cycles at 0.5 C for SIBs, while VCA‐5 manifests a superior capacity of ≈258 mAh g−1 at 0.1 C with an 82.7% retention over 1000 cycles at 0.5 C for PIBs. Moreover, their full cells demonstrate the promising potential of VCAs in applications. This novel controllable ice‐templating strategy opens unique avenues to tune the construction of hollow aligned channels for shortening ion‐transport pathways and ensuring structural integrity. New insights into structure‐performance correlations regulated by the cooling rates of an ice‐templating strategy and design guidelines for electrodes applicable in multiple energy storage technologies are reported.
A novel controllable ice‐templating strategy is utilized to tailor low‐cost cellulose nanocrystal/polyethylene oxide‐derived, vertically aligned carbon aerogels (VCAs) as anodes of sodium‐ and potassium‐ion batteries. The construction of hierarchically tailored channels is tuned for shortening ion‐transport pathways and ensuring structural integrity. These sustainable VCAs can be easily extended to multiple energy storage systems, demonstrating their universal potential.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Biomass is recognized as an ideal CO2 neutral, abundant, and renewable resource substitute to fossil fuels. The rich proton content in most biomass derived materials, such as ethanol, ...5‐hydroxymethylfurfural (HMF) and glycerol allows it to be an effective hydrogen carrier. The oxidation derivatives, such as 2,5‐difurandicarboxylic acid from HMF, glyceric acid from glycerol are valuable products to be used in biodegradable polymers and pharmaceuticals. Therefore, combining biomass‐derived compound oxidation at the anode and hydrogen evolution reaction at the cathode in a biomass electrolysis or photo‐reforming reactor would present a promising strategy for coproducing high value chemicals and hydrogen with low energy consumption and CO2 emissions. This review aims to combine fundamental knowledge on photo and electro‐assisted catalysis to provide a comprehensive understanding of the general reaction mechanisms of different biomass‐derived molecule oxidation. At the same time, catalyst requirements and recent advances for various feedstock compounds are also reviewed in detail. Technoeconomic assessment and life cycle analysis are performed on various feedstocks to assess the relative benefits of various processes, and finally critical prospects are given on the challenges and opportunities for technology development to meet the sustainability requirement of the future global energy economy.
This review summarizes recent research progress in photo‐ and electrochemical oxidation of biomass feedstocks for the production of chemicals and hydrogen. High‐level technoeconomic assessment and life cycle analysis are performed to evaluate the economic value and environmental impact of biomass electrolysis. Based on the outcomes, perspectives on current technical challenges and future opportunities are provided.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sustainable energy production at an acceptable cost is key for its widespread application. At present, noble metals and metal oxides are the most widely used for electrocatalysis, but they suffer ...from low selectivity, poor durability, and scarcity. Because of this, metal‐free carbons have become the subject of great interest as promising alternative electrocatalysts for energy conversion and storage devices, and remarkable progress has been accomplished in the advance of metal‐free carbons as electrocatalysts for renewable energy technologies. Particularly interesting are 3D porous carbon architectures, which exhibit outstanding features for electrocatalysis applications, including broad range of active sites, interconnected porosity, high conductivity, and mechanical stability. This review summarizes the latest advances in 3D porous carbon structures for oxygen and hydrogen electrocatalysis. The structure–performance relationship of these materials is consequently rationalized and perspectives on creating more efficient 3D carbon electrocatalysts are suggested.
Metal‐free carbon‐based materials with a 3D porous architecture are earmarked to be the platform for the next generation of electrocatalysts in energy conversion and storage technologies. This review highlights the latest findings in 3D porous carbon nanostructured materials, main challenges, and future directions for further development of these exciting materials into highly performing oxygen and hydrogen electrocatalysts.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The production of functional nanostructured materials starting from cheap natural precursors using environmentally friendly processes is a highly attractive subject in material chemistry today. ...Recently, much attention has been focused on the use of plant biomass to produce functional carbonaceous materials, encompassing economic, environmental and social issues. Besides the classical route to produce activated carbons from agricultural side products, the hydrothermal carbonization (HTC) process shows clear advantages in that it can generate a variety of cheap and sustainable carbonaceous materials with attractive nanostructure and functionalization patterns for a wide range of applications. In this tutorial review we present the latest developments in this traditional but recently invigorated technique. It will be shown that HTC does not only access carbonaceous materials under comparatively mild hydrothermal conditions, but also replaces the more technical and structurally well-defined charring by a controlled chemical process. It will be shown that this makes it possible to tailor the final structure with the tools of colloid and polymer science, leading to very different morphologies with miscellaneous applications, including modern carbon nanocomposites and hybrids.
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