Sustainable Energy & Fuels最新文献

Biohydrogen production from food waste offers a sustainable and carbon-neutral alternative to fossil fuels. However, its large-scale application is limited by the rapid hydrolysis of biodegradable organics, resulting in the accumulation of inhibitory byproducts such as ammonia and volatile fatty acids (VFAs), especially lactic acid. These compounds suppress hydrogen-producing bacteria and reduce system efficiency. Integrating dark fermentation (DF) with microbial electrolysis cells (MECs) has emerged as a promising approach to overcome these limitations by converting residual organics into additional hydrogen via electrohydrogenesis. Optimization of operational parameters such as pH, hydraulic retention time (HRT), and organic loading rate (OLR) further enhances hydrogen yield by minimizing VFA accumulation and improving system stability. Integrated DF–MEC systems have achieved hydrogen yields of up to 1608.6 ± 266.2 mL H₂ per g COD consumed and COD removal efficiencies of 78.5 ± 5.7%. Heat pretreatment and the use of genetically engineered microbial strains have been shown to further enhance hydrogen production. Engineered strains have delivered hydrogen yields ranging from 0.47 to 1.88 mol H₂ per mol glucose. MEC integration has also demonstrated a 30–40% increase in hydrogen production compared to standalone DF systems. The digestate from lactate-driven DF, enriched with VFAs such as acetate and lactate, provides an excellent substrate for MECs, thereby enhancing electrohydrogenesis. Despite high initial capital costs, the long-term benefits, such as waste valorization, greenhouse gas reduction, and renewable energy recovery, make the DF–MEC system a viable and scalable solution for sustainable hydrogen production from food waste.

Microbial fuel cells (MFCs) represent a promising green technology for energy recovery from organic waste. In this study, we developed biodegradable composite proton exchange membranes (PEMs) based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) reinforced with reduced graphene oxide (rGO) using a solution casting method. The membranes were systematically characterized and tested in a dual-chamber MFC system. The membrane doped with 7 wt% rGO showed a proton conductivity of 23.3 mS cm⁻¹ at 80 °C, a water uptake of 7.71% and a low oxygen permeability of 2.43 × 10⁻⁴ cm s⁻¹. This membrane achieved a power density of 71.3 mW m⁻², outperforming the commercial Tion5-W membrane by approximately 50%. The integration of rGO improved thermal, mechanical and electrochemical performance while maintaining the biodegradability of the membrane matrix. These findings highlight the potential of rGO/P3HB4HB membranes as a high-performance and environmentally sustainable alternative to conventional perfluorinated PEMs, especially in decentralized wastewater-to-energy applications.

Heteroatom-doped carbon nanomaterials are commonly employed as electrode materials for supercapacitors (SCs) due to their high accessible surface area, tunable surface chemistry, and unique electronic structures. However, they are generally prepared in fine powdery forms from expensive high-purity metal catalyst and carbon precursors via a tedious synthetic process, limiting their practical application. Herein, we develop a monolithic electrode, denoted as Fe@NCNTs/RB, by directly growing high-density N-doped carbon nanotubes (NCNTs) with encapsulated Fe nanoparticles within a red brick (RB) substrate via the chemical vapor deposition (CVD) method using melamine as the sole C and N sources. During the CVD process, the endogenous Fe species within the RB substrate act as efficient self-generated catalysts for catalyzing the in situ growth of high-density NCNTs from melamine pyrolysis, avoiding the use of external high-purity metal catalysts. The as-fabricated Fe@NCNTs/RB electrode is electrically conductive and mechanically strong and can be directly used as a binder-free electrode for SCs, exhibiting a high areal capacitance (C_a) of 918.75 mF cm⁻² at 1.0 mA cm⁻² and an excellent rate capability with 34% capacitance retention at 20 mA cm⁻². Notably, a symmetric SC assembled with an Fe@NCNTs/RB electrode delivers a high C_a of 277.48 mF cm⁻² at 1.0 mA cm⁻², an energy density of 11.13 μWh cm⁻² at a power density of 269.25 μW cm⁻² within a potential window of 0–1.1 V, and excellent cycling stability after 50 000 cycles with 92% capacitance retention and a unit coulombic efficiency at 10 mA cm⁻². This work paves a new way for the development of cost-effective and practically applicable monolithic electrodes for high-performance SCs.

Correction for “Sustainable aviation fuel production via the methanol pathway: a technical review” by Ali Elwalily et al., Sustainable Energy Fuels, 2025, https://doi.org/10.1039/D5SE00231A.

Various electrolyte designs have been explored to enhance the temperature dependence of the redox potential (Seebeck coefficient) as it determines the cell voltage of thermo-electrochemical devices such as thermally regenerative electrochemical cycles (TRECs). TRECs require redox couples with both high positive and negative Seebeck coefficients to achieve high performance. In our previous study, ferrocyanide/ferricyanide in a mixture of water and tetrabutylammonium fluoride (TBAF) exhibited a high negative Seebeck coefficient owing to the formation and dissociation of semiclathrate hydrate (SCH) induced by temperature variations. In this study, we found that the formation and dissociation of SCH can also provide a high positive Seebeck coefficient (+16 mV K⁻¹) by increasing the weight ratio of TBAF in the electrolyte. The key factor influencing the increase in the Seebeck coefficient is the change in TBAF concentration in the liquid phase, which significantly affects the redox potential of ferrocyanide/ferricyanide. When the TBAF weight ratio in the electrolyte exceeds that of SCH, the effect of SCH formation on the TBAF concentration in the liquid phase is reversed. Therefore, incorporating SCH can enhance the Seebeck coefficient in both positive and negative directions by tailoring the mixing ratio of TBAF. Additionally, we demonstrated a proof-of-concept TREC using the two electrolytes with high positive and negative Seebeck coefficients. The cell demonstrated a significant temperature dependence of the open-circuit voltage, allowing for a much higher average discharge voltage (271 mV) than charge voltage (145 mV), with a small temperature difference between the charge (299 K) and discharge (294 K) processes.

This article is a comment on N. Chapuis and L. Bocquet [Sustainable Energy Fuels, 2025, 9, 2087–2097]. In this work, the authors present an experimental process that shows how it is possible to set up a reverse electrodialysis cell capable of achieving power values of 5 W m⁻². This value is the profitability threshold. Our work challenges this claim and questions whether the proposed technique can be scaled up.

This study introduces a direct methanol hydrogen peroxide fuel cell (DMHPFC) using a pH-gradient-enabled microscale bipolar interface (PMBI) to address limitations in direct methanol fuel cells (DMFCs). Unlike conventional fuel cells that use oxygen, the DMHPFC utilizes H₂O₂, enhancing reactant availability and reaction kinetics. The PMBI maintains separate pH environments at the anode and cathode. The PMBI-DMHPFC combines an alkaline anode for methanol oxidation and an acidic cathode for hydrogen peroxide reduction, achieving a theoretical open-circuit voltage (OCV) of 1.72 V (compared to a theoretical OCV of 1.25 V for DMFCs) and a volumetric energy density of 9.2 kWh l⁻¹ using aqueous methanol (39% vol) and hydrogen peroxide (41% vol). This energy density quadruples that of compressed hydrogen (2.1 kWh l⁻¹ at 69 MPa). This study identifies optimal operating conditions: 5 M methanol with 3 M KOH as anolyte, 5 M hydrogen peroxide with 1.5 M sulfuric acid as catholyte, Nafion 115 (127 μm) as membrane, and flow rate of 2.5 ml min⁻¹ cm⁻² – that maximize the power output and minimize activation-, ohmic- and mass transfer losses in DMHPFCs. Performance evaluation reveals a measured OCV of 1.69 V. While the PMBI-DMHPFC surpasses DMFC performance, its high OCV and energy density are not fully translated into high power density due to significantly higher activation and mass transport losses compared to H₂–O₂ fuel cells, which typically achieve peak power densities above 1000 mW cm⁻². The DMHPFC achieves a peak power density of 630 mW cm⁻² at the unusually high voltage of 0.8 V, reflecting the unique PMBI design and optimized operating conditions that reduce losses. This steeper voltage drop is attributed to sluggish reaction kinetics, membrane crossover and mass transport limitations. It highlights the potential for improved performance through advanced electrocatalysts, optimized membrane materials and flow design from this promising baseline.

Transparent radiative cooling materials possess spectrally selective optical characteristics: they exhibit excellent transmissive performance in the visible spectrum range to allow visible light to pass through while demonstrating high emissivity in the atmospheric window. As an inherent property of materials, emissivity is defined as the ratio of radiant power per unit area of a material to that of a blackbody (an ideal radiator) at the same temperature under thermal equilibrium, and it is closely related to thermal radiation. According to Kirchhoff's law, emissivity equals absorptivity under thermal equilibrium conditions. Based on the above characteristics, such materials provide crucial support for sustainable cooling technologies and show broad prospects in the field of green and low-carbon cooling. This paper systematically reviews the principles, material systems, and design strategies of such coolers, focusing on their recent advancements. We comprehensively discuss material selection (hydrogels and thin films), structural design (inorganic materials, photonic crystal multilayers, and metamaterial architectures), performance optimization strategies (enhancing infrared emissivity in the atmospheric window), and their applications in smart windows, energy-efficient buildings, and electronics cooling. Future research should address scalability and durability through cross-scale designs and bio-inspired functionalities, further advancing this field. Ultimately, transparent radiative cooling offers an eco-friendly and energy-efficient solution to meet growing global cooling demands.

The performance of LIBs deteriorates over time due to various aging mechanisms, among which lithium plating (LP) is critical. This study investigates LP in commercial high-energy graphite-SiO_x/NMC pouch LIBs cycled until end-of-life (EOL) under LP-inducing conditions. Employing post-mortem analysis techniques such as ⁷Li nuclear magnetic resonance (NMR) spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES), and scanning electron microscopy (SEM), we aim to provide a comprehensive understanding of LP. Electrochemical methods such as incremental capacity analysis (ICA) and differential voltage analysis (DVA) were first used to identify LP occurrence in a cell during artificial ageing (AA). Subsequently, the cells were dissected to prepare post-mortem analysis samples. ICP-OES revealed an increased soluble lithium (Li) content on the anode surface compared to a fresh cell, which is attributed to LP. Metallic Li was identified on the anode surface of the cycled cell by ⁷Li NMR at Knight shifts in the range from 245 to 270 ppm, whereas no metallic Li was detected in fresh cell. Post-mortem SEM analysis revealed a mossy layer growth on anode sample of the artificially aged cells that is absent on the anode surface of a fresh cell. This mossy growth is attributed to LP. Elemental mapping also revealed fluorine hotspots on the mossy metallic Li layer, indicating the formation of lithium fluoride (LiF) as a reaction product between metallic Li and the cell electrolyte. Additionally, as the SEM sample was exposed to air during transfer, oxygen hotspot on mossy Li layer in elemental mapping indicates the reaction of oxygen and moisture with metallic Li.

An eco-friendly and cost-effective reflux approach is employed to synthesize ZnO-doped NiCo₂O₄ (NCOXZnO) nanocomposites for supercapacitor applications. Advanced sophisticated tools are employed to investigate the structure, surface morphology, magnetic properties, surface area, and optical characteristics of NCOXZnO nanocomposites to validate their purity. The findings revealed that doping of ZnO significantly influenced the particle size, paramagnetic behaviour, porosity, and active surface area of the pristine NCO material. Electrochemical studies show that NCO7ZnO with 7 wt% ZnO achieves optimal performance, with a specific capacitance of 293 F g⁻¹ at a specific current of 0.5 A g⁻¹ and 439 F g⁻¹ at a scan rate of 1 mV s⁻¹ in 0.5 M H₂SO₄, surpassing pristine NCO. The NCO7ZnO nanocomposite also shows a high surface area (100.755 m² g⁻¹), higher pore volume (0.148 cm³ g⁻¹), and low charge transfer resistance (R_ct = 0.68 Ω). Additionally, the symmetric supercapacitor device using NCO7ZnO has a superior specific energy of 34.35 W h kg⁻¹ at a specific power of 200 W kg⁻¹. Furthermore, it demonstrates an impressive cycle stability of 98% over 10 000 cycles, positioning ZnO-doped NiCo₂O₄ as a highly promising candidate for next-generation supercapacitors.