Sustainable Energy & Fuels最新文献

Biomass-derived 5-hydroxymethylfurfural (HMF) represents a crucial platform molecule in the advancement of sustainable chemical production, being produced via acid-catalysed dehydration of sugars. This study investigates the impact of three supported organic acids, namely sulphonic (RSO₃H/stellate), phosphonic (RPO₃H₂/stellate), and carboxylic (RCOOH/stellate) acids, grafted on mesoporous silica nanospheres. Deployment of these as catalytic species facilitates the evaluation of acid strength on HMF dehydration and the impact on subsequent undesirable side reactions, including polyfuranic humin formation. While increased acid strength promotes higher fructose conversion, the weaker carboxylic acid catalysts consistently exhibit superior long-term selectivity towards HMF. Maintaining high HMF selectivity is reliant on preventing further reactions of it, with acid-catalysed aldol condensations yielding humins more favourably over stronger acid sites. After 45 min at 165 °C, HMF selectivity is greater for RCOOH/stellate (85% at 53% conversion) relative to RSO₃H/stellate (78% at 83% conversion) and RPO₃H₂/stellate (71% at 91% conversion). As reaction temperature escalates, a trade-off between elevated conversion and diminishing selectivity is apparent for all catalytic materials. At 185 °C, conversion reaches 70% in only 5 min with HMF selectivity of 89%, but at the expense of reduced long-term process selectivity (HMF selectivity ∼23% at 45 min). The catalyst's green credentials are further apparent from a facile reactivation protocol, which restores >85% of the initial catalyst activity.

Fermentative production of 2,3-butanediol (BDO) offers a sustainable alternative to fossil-based chemical synthesis, but its economic feasibility strongly depends on the use of low-cost feedstocks and efficient microbial strains capable of utilizing mixed sugars. In the current study, Klebsiella pneumoniae was used to produce BDO from arabinose and glucose-rich fractions derived from sugar beet pulp (SBP), a major sugar industry waste. Initial shake-flask studies revealed efficient BDO formation from arabinose, although fermentation performance was declined at higher concentrations (60 g L^-1) due to substrate inhibition. The strain was subjected to adaptive laboratory evolution (ALE) to overcome this limitation. The evolved strain (A4) showed enhanced arabinose utilization and achieved a productivity of 0.54 g L^-1 h^-1 at 100 g L^-1 arabinose compared with 0.43 g L^-1 h^-1 for the parent strain. The fed-batch bioreactor cultivation of the evolved strain resulted in BDO titers of 84.9 and 96.7 g L^-1 with a conversion yield of 0.39 g g^-1 using arabinose- and glucose-rich mixture of pure sugars, respectively. During fed-batch cultivation, the strain accumulated 82.2 and 92.4 g L^-1 BDO from arabinose- and glucose-rich SBP hydrolysates, respectively, with a conversion yield of 0.38 g g^-1. The pasteurization of SBP hydrolysates significantly improved fermentation kinetics, which resulted in the shortening of fermentation times by 30-40 h while maintaining the BDO titer and yield comparable to the non-pasteurized hydrolysate. Overall, BDO production from pure sugars and sugar-rich hydrolysates from SBP was similar. These results demonstrate the immense potential of the isolate K. pneumoniae as a biofactory in valorizing SBP into BDO with possibility for future industrialization.

Membrane-photoelectrode assemblies are a promising device configuration to directly electrolyse liquid water or water vapour into hydrogen and oxygen using solar energy. For the first time, we studied the performance and the stability of membrane-photoelectrode assemblies with BiVO₄ photoanodes and CoPi co-catalysts on metallic felt at different temperatures. Upon illumination with simulated solar light, photocurrent densities of 0.23 mA cm^-2 at 1 V vs. RHE were obtained with the proton-exchange ionomer and 0.06 mA cm^-2 with the anion-exchange ionomer, all using liquid water at 30 °C. Operation with liquid water at 56 °C reduced the onset potential difference under light and in the dark due to more severe recombination of charges, independent of the choice of ionomer. The (photoelectro)chemical corrosion reactions resulted in the dissolution of Bi, V, Mo and Co, which was accelerated by temperature. The dissolved species formed solid particles mainly containing vanadium in the proton-exchange membranes. Operation of proton-exchange membrane-photoelectrode assemblies with water vapour resulted in an 85% decrease in the photocurrent density produced at 1 V vs. RHE as the hydration of the ionomer was reduced. The more acidic local pH at the ionomer-photoelectrode interface (compared to liquid water operation) accelerated the dissolution of the photoactive material in time, resulting in a faster decrease in the saturation current density. Membrane-photoelectrode assemblies have been demonstrated to expand practical device configurations beyond conventional planar setups. The remaining performance gap with respect to planar photoelectrodes highlights the gains that systematic optimisation of membrane-photoelectrode assemblies can still unlock.

Highly active palladium-doped spinel zinc cobalt selenide (PZCS)-coated nickel foam (ZnPd_xCo_2−xSe₄ (x ≤ 0.08)@NF) nanoelectrocatalysts were prepared via a two-step hydrothermal method. The spinel phases of the engineered samples were confirmed by X-ray diffraction, revealing a microsphere surface morphology with a dense nanofeather configuration. Chronopotentiometry measurements of the prepared nanoelectrocatalysts revealed their excellent hydrogen evolution reactivity, low overpotential (∼64 mV, similar to that of the benchmark Pt catalyst), low Tafel slope (∼55.61 mV dec⁻¹), and long-term stability exceeding 24 h. An electrochemical study with 6.0% Pd doping indicated higher hydrogen evolution efficacy, attributed to the increased surface area and accelerated charge-transfer kinetics at the semiconductor electrolyte interface. Methanol oxidation (MO), urea oxidation (UO), and MO-/UO-assisted water splitting analyses confirmed the optimal performance with 6.0% Pd. Density functional theory calculations were performed to evaluate the effects of Pd dopants on the catalytic activity of ZnCo₂Se₄ (ZCS). The hydrogen, water, and methanol adsorption energies on ZCS and PZCS demonstrated consistently exothermic interactions at all surface sites. Therefore, the incorporation of Pd enhanced hydrogen and water adsorption while preserving the weak binding toward methanol that remained non-competitive with hydrogen adsorption. The computed hydrogen adsorption free energies suggested near-optimal values (approximately −0.44 eV) at the Pd site, designating it as the active center for hydrogen evolution reactivity. The simulated electronic density of states indicated supplementary energy-level contributions from Pd near the Fermi level, improving electronic conductivity and charge transfer during electrocatalysis. Thus, Pd-doped ZCS enhanced the electronic properties of the nanoelectrocatalyst active surface, providing suitable candidates for coupled hydrogen evolution and MO-/UO-assisted water splitting.

Electrochemical water splitting is a key technology for sustainable green hydrogen (H₂) production, yet its large-scale operation demands earth-abundant and cost-effective electrocatalysts capable of functioning efficiently with sufficiently low overpotentials with significant durability. In this scenario, copper-based molecular complexes are emerging catalysts which show promising results in the field of electrocatalytic green hydrogen evolution reaction (HER). It can be anticipated that these complexes upon further modification could replace noble-metals in coming years owing to their inexpensiveness, physicochemical tunability and industrial-scale compatibility. This review comprehensively consolidates and analyses the latest advances in copper-based molecular electrocatalysts for the HER, mainly featuring homogeneous complexes composed of polydentate N-donor, N/S-donor and N/O-donor ligands, as well as molecular precursors that are converted into catalytically active heterogeneous Cu species during electrolysis. It further meticulously summarizes various strategic ligand engineering approaches through proton-responsive functional groups and bioinspired coordination motifs, allowing technologically relevant catalytic performances featuring mainly turnover frequencies exceeding 10⁴ s⁻¹ and faradaic efficiencies approaching 98% across pH of ∼2–14. Beyond performance metrics, this review dives deep into mechanistic insights resulting from kinetic analyses, spectroelectrochemical studies, and density functional theory calculations to explicate proton-coupled electron transfer (PCET) pathways involving transient Cu-hydride intermediates or ligand-assisted protonation steps that optimize adsorption–desorption energetics for faster kinetics. Particular emphasis is placed on the technological translation of molecular catalysts into practical systems, including catalyst immobilization on conductive substrates, molecular-to-heterogeneous catalyst transformation and integration within electrode architectures relevant to overall water electrolyzers. Crucial challenges such as catalyst stability, structural evolution under operating conditions and the need for standardized benchmarking protocols are explicitly discussed. Collectively, this review provides a roadmap for rationally designing robust Cu-molecular electrocatalysts and highlights their potential to enable cost-effective and scalable green H₂ production technologies through electrolysis.

Vanadium redox flow batteries (VRFBs) are promising for large-scale energy storage, yet their performance is often constrained by sluggish kinetics and ohmic losses of conventional graphite felt electrodes. Herein, we report a sequential chromium carbide-based surface engineering strategy involving thermal treatment, chromium precursor impregnation and high-temperature carburization to form conductive Cr₃C₂ anchored to the graphite felt fibers, and a subsequent post-oxidation-assisted hydrophilization (HPZ) step that generates a thin Cr₂O₃ surface layer while restoring surface polarity. XRD, SEM, and TEM analyses indicate the presence of Cr₃C₂ on the graphite fibers with an oxidized surface layer, resulting in a Cr₃C₂/Cr₂O₃ dual-phase surface that provides a favorable balance between electronic conductivity and electrolyte wettability compared with a Cr₂O₃-only modification. XPS reveals pronounced surface deoxygenation and defect enrichment after carburization, whereas HPZ reintroduces oxygen-containing functional groups. Electrochemical impedance spectroscopy demonstrates concurrent mitigation of kinetic and ohmic losses: the TT electrode exhibits an R_ct of 11.86 Ω and an R_s of 0.225 Ω, while the CB + HPZ electrode delivers much lower values of 2.8 Ω and 0.025 Ω, respectively. CV analysis further supports a more balanced and reversible vanadium redox response for CB + HPZ than OX. Consequently, the engineered electrode achieves ∼88% energy efficiency at 50 mA cm⁻² and sustains operation at 250 mA cm⁻² with ∼64% energy efficiency. Long-term cycling at 100 mA cm⁻² maintains energy efficiency above 80.8% with 97.6% retention over 200 cycles, while coulombic efficiency remains consistently >98%, indicating stable performance under prolonged operation. Post-cycling SEM/EDS confirms that Cr-containing particles remain on the graphite felt fibers after 200 cycles, supporting electrode durability.

Semiconductors underpin many modern technologies, from data processing and displays to power generation, and their performance relies on precise thin-film deposition processes. These processes control the composition and interfaces between device layers, ensuring that semiconducting materials function reliably without degradation. In high-value devices such as perovskite solar cells, variations in deposition methods can significantly affect both material use and product quality. Improving the precision, consistency, and sustainability of thin-film deposition is therefore essential to enable scalable, efficient, and environmentally responsible manufacturing. This study employs a process-based Life Cycle Assessment (LCA), extended to include activity-level steps, to evaluate environmental impacts across laboratory- and pilot-scale perovskite solar cell production. The analysis highlights energy consumption in processing equipment and facility operations as the dominant environmental burden, with the deposition stage representing a key target for efficiency improvements. Scaling from laboratory to pilot-scale production reduces perovskite solar cell manufacturing costs by approximately 99.8% per m² of active area, with an additional ∼8% reduction achieved through enhanced process control. At this scale, environmental impacts decrease by over 98% across global warming potential, human toxicity and aquatic ecotoxicity. Further integration of automated control systems lowers global warming and toxicity impacts by around 10%, while substituting grid electricity with low-carbon wind power amplifies these gains, reducing carbon emissions by up to 79%. The results demonstrate that combining process optimization with renewable energy sourcing provides a clear pathway toward sustainable, scalable perovskite solar cell manufacturing. The methodology is also broadly applicable to other thin-film semiconductor processes, offering guidance for improving operational efficiency while minimizing environmental impact.

The growing demand for sustainable recycling of spent lithium-ion batteries necessitates environmentally friendly processes for the efficient recovery of valuable metals. Herein, we present a green and facile strategy that integrates high-temperature oxidation with phosphoric acid leaching to recover α-Fe₂O₃ and Li₃PO₄ from spent lithium iron phosphate (LiFePO₄) batteries. The process involves dismantling, followed by oxidation of the cathode material at 600 °C under O₂ to remove impurities and oxidize Fe²⁺ to Fe³⁺, and subsequent leaching with 2 mol per L H₃PO₄ (liquid-to-solid ratio of 10 : 1, 60 °C, 4 h). Subsequent pH adjustment to 6 precipitates Fe³⁺, and the residue is mixed with NH₄H₂PO₄ and calcined at 700 °C to yield α-Fe₂O₃. The filtrate is concentrated and adjusted to pH 12 to precipitate Li₃PO₄. Comprehensive characterization confirms the morphology, phase purity, and magnetic properties of the obtained products. The α-Fe₂O₃ consists of uniform quasi-spherical particles (∼90 nm) with a purity of 96.27% and a recovery yield of 91.38%, while Li₃PO₄ forms hexagonal prismatic crystals (1–2 µm) with 94.58% purity and 92.53% yield. Magnetic measurements show a remnant magnetization of 0.001 emu g⁻¹ and coercivity of 10.39 Oe at low temperature, and 0.10 emu g⁻¹ and 1072.8 Oe at room temperature for α-Fe₂O₃. This pH-gradient separation approach provides a robust, low-cost pathway for valorizing spent LiFePO₄ batteries, advancing circular economy principles and mitigating environmental impacts of electronic waste.

Two-dimensional halide perovskites are emerging optoelectronic semiconductors because of their tunable photophysical characteristics and enhanced environmental stability relative to three-dimensional perovskites. Herein, we design perovskite solar cells in which both charge transporting layers and the perovskite are on two-dimensional semiconductors, providing atomically sharp interfaces and suppressed interfacial defects. The proposed solar cells employ a Dion–Jacobson perovskite with a thiophene-based bulky diammonium aromatic spacer, (ThDMA)MA_n−1Pb_nI_3n+1 with nominal n = 5, which is combined with molybdenum disulfide and tungsten disulfide as electron and hole charge transporting layers. After optimization of the perovskite layer of the designed solar cells, the n = 5 Dion–Jacobson device delivers a champion efficiency of 17.13% with a remarkably high open-circuit voltage of 1.25 V and a fill factor of 81.07%. The high device performance was achieved with a perovskite layer thickness of 200 nm, trap-state density of 10¹⁴ cm⁻³, charge carrier mobility of 0.1 cm² V⁻¹ s⁻¹, series resistance of 2.0 ohm cm², shunt resistance of 5000 ohm cm², and operating temperature of 300 K. Importantly, the optimized cell maintained 83% of its original efficiency at 400 K. This work provides significant directions for future advancements toward high-performance low-dimensional perovskite photovoltaics.

Li-metal deposition represents a critical degradation pathway in Li-ion batteries, rendering real-time monitoring of this process essential for ensuring safe operation. In this study, Li-metal deposition and dissolution are monitored using a sensor that measures the real part of the impedance (Re(Z)) in the MHz range. The MHz-range Re(Z) is highly sensitive to Li-metal, enabling compact sensor implementation and rendering it well-suited for monitoring applications. Thus, a highly accurate sensor is developed to monitor Li-metal deposition and dissolution dynamics. For proof of principle, an operando cross-sectional observation cell with sensor monitoring is employed to validate the ability to capture Li-metal dynamics. It is also confirmed that this approach is effective for application in commercial 18 650 cells, and cycle testing demonstrates that deposition and dissolution evolve with degradation. This work provides a robust tool for investigating Li-metal dynamics and offers a pathway for real-time monitoring of safer and more reliable battery systems.