Sustainable Energy & Fuels最新文献

The advancement in the field of solar energy conversion devices has led to the development of both energy generation and energy storage technologies. However, a hybrid device capable of both generation and storage is still in its infancy. In this work, a multi-layered twin electrode photocapacitor has been developed which is free of metal ions and electrolyte. The device was composed of an active layer of CdSe quantum dots (QD) embedded in a polymer matrix and sandwiched between multi-layered stacking (MLS) of rGO and TiO₂. An ultrafast charging time of 3–5 s was achieved under 1 sun illumination with a discharge time of over 500 s under load. An optimized capacitance of 307.4 mF g⁻¹ was obtained under load while 6022 mF g⁻¹ capacitance was obtained under load and LED illumination with ∼88% retention capacity after 200 cycles. Additionally, the device was also able to partially harness low intensity radiation (∼60 lux).

The use of microorganisms to convert food waste into high-value products is a promising biorefinery approach for not only the reduction of food waste but also its recycling and valorisation. Moreover, microalgae are increasingly recognised as cellular factories capable of producing various value-added metabolites by utilising organic nutrients. In this regard, this study examined different food waste with distinct carbon-to-nitrogen ratios as nutrient sources for the production of diverse value-added products via mixotrophic cultivation of the microalga Isochrysis galbana. It was demonstrated that, while both hydrolysates enhanced the microalgal growth compared to the autotrophic cultivation, steamed bun waste hydrolysate with a high carbon-to-nitrogen ratio led to improved lipid accumulation and the nitrogen-rich shrimp waste hydrolysate favoured the production of fucoxanthin. Based on these experimental results, techno-economic analyses were conducted and demonstrated that the strategies examined on a laboratory scale would be economically viable at pilot-plant scale, especially if a nitrogen-rich hydrolysate such as that derived from shrimp waste were used, as this promotes microalgal growth. This study highlighted the significance of adopting various kinds of food waste in microalgae-based biorefineries, and hopes to provide insights to relevant sectors from both experimental and economic perspectives.

Solution-processed technologies for (semi)transparent top electrodes remain suboptimal, although see-through perovskite solar cells (s-PSCs) are required in realizing window-integrated photovoltaics. Herein, we choose an inorganic perovskite, CsPbBr₃, offering the best matching example with wavelength-selective transparency and weatherability, and present the simplest s-PSC excluding organic components, fluorine-doped tin oxide (FTO)/TiO₂/CsPbBr₃/single-walled carbon nanotube (SWNT). The semitransparent electrode is realized by solution-processed filter-transferred SWNT thin films with different transmittances of 60–80%T at 550 nm. The diode ideal factors range between 1 and 2, suggesting high heterojunction qualities as a single-diode model with hole-transfer-layer-free CsPbBr₃/SWNT. Under monofacial pseudo-sunlight irradiation through FTO, the increased electrical conductivities (densities) of SWNT improve power-conversion efficiencies/short-circuit currents, PCEs (FTO)/J_sc = 8.68/7.49 (60) > 8.18/7.33 (70) > 7.30%/6.91 mA cm⁻² (80%T). Through SWNT, the increased transparency improves PCEs (SWNT)/J_sc inversely as 4.21/3.79 (60) < 4.45/4.13 (70) < 4.56%/4.56 mA cm⁻² (80%T). Open-circuit voltages/fill factors are 1.48/0.79 through FTO and 1.33 V/0.84 through SWNT (60%T). A tradeoff exists between the conductivities and transparency to achieve high performance. Bifacial irradiation using light-emitting diodes shows close values of PCEs (bifacial) = 3.67 (60), 3.86 (70), and 3.71% (80%T) based on 32–35% of pseudo-sunlight power (100 mW cm⁻²), equivalent to the sums of the monofacial-irradiation PCEs (FTO) and PCEs (SWNT). Enhancement ratios of PCEs (bifacial) to PCEs (SWNT)/to PCEs (FTO) are 3.19/1.36 (60), 3.04/1.46 (70), and 2.81/1.53 (80%T). The bifacial function solves the monofacial tradeoff. The black color of SWNT is not a serious obstacle visually under exterior environments.

The absorption and desorption behaviours of NH₃ in bis(trifluoromethylsulfonyl)amide (TFSA) salts were investigated using the pressure-swing method. The effects of cation species and temperature on the NH₃ absorption behaviour of four TFSA salts, namely, Na[TFSA], K[TFSA], Mg[TFSA]₂, and Ca[TFSA]₂, were evaluated. NH₃ was absorbed by these solid TFSA salts, and high NH₃ desorption was observed for Na[TFSA] at 473 K and K[TFSA] at 300 K. The NH₃ absorption behaviour varied with the cation of the TFSA salt. Crystallographic refinement showed that the crystal lattice of Na[TFSA] expanded and contracted along the c-axis upon NH₃ absorption and desorption, respectively, indicating the coordination of NH₃ molecules with cation sites between the lattice layers. For the alkaline-earth metal TFSA salts, NH₄[TFSA] and amide compounds (Mg(NH₂)₂ or Ca(NH₂)₂) were formed after NH₃ absorption. Therefore, two absorption processes—coordination and dissociation of NH₃—occurred in the TFSA salts.

Small organic molecules have garnered significant attention as hole-transporting materials (HTMs) in perovskite photovoltaic (PPV) devices due to their enhanced stability, cost reduction, and improved performance. To achieve optimal performance in PPVs, 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD) currently is the leading HTM but its instability over a prolonged period is insufficient for ensuring reliable long-term device operation, and the current high market price poses a barrier to its uninterrupted use in large-scale manufacturing. In this work, we synthesized and characterized two novel small organic molecules based on the central [1]benzothieno[3,2-b][1]benzothiophene (BTBT) core, termed BTBT-1 and BTBT-2, and applied as HTMs in indoor PPVs (i-PPVs). The dopant-free BTBT-2 demonstrated a power conversion efficiency (PCE) of 31.73%, which is higher than that of a device using BTBT-1 (29.19%) and doped Spiro-OMeTAD (28.87%) under the illumination of a 1000 lux LED lamp. Conspicuously, the hydrophobic nature of the BTBT-2 based dopant-free HTM afforded excellent stability compared to Spiro-OMeTAD doped i-PPVs, which enables better moisture resistance and long-term stability under indoor conditions. These results suggest that BTBT-2 is a promising candidate for high-performance, stable indoor photovoltaic technology, offering a cost-effective and reliable alternative for large-scale applications.

Lactones are an interesting category of sustainable fuels since they have the same carbon backbones as sugars but are liquids at room temperature. Engine studies have shown that lactones can reduce soot emissions as well as net carbon dioxide emissions. In this study quantitative sooting tendencies were measured for 10 lactones with a wide range of molecular structures. They included compounds with ring sizes varying from three to six carbons, unsubstituted compounds, substituted compounds with side chain lengths ranging from one to seven carbons, and one compound with a double bond in the ring. Two alkenoic acids were also tested since they are possible isomerization products of lactones. The sooting tendencies were characterized by yield sooting index (YSI), which is based on the soot yield when a methane/air nonpremixed flame is doped with 1000 μmol mol⁻¹ of the test fuel. The results show that the lactones have lower sooting tendencies than conventional gasoline, diesel fuel, and Jet A aviation fuel, even when accounting for their lower heats of combustion. However, the sooting tendencies depend strongly on molecular structure, so the right lactones must be chosen to maximize the emissions benefits. The measured sooting tendencies are generally larger than those predicted with a group contribution method, which indicates that the lactones have high sooting tendencies given the set of atoms they contain. To explain this observation, reactive molecular dynamics simulations and quantum chemistry calculations were performed. The results show that the lactones tend to decompose directly to CO₂, so the oxygen atoms are being used inefficiently to sequester only one carbon atom.

Chemical looping dry reforming of methane (CL-DRM) is an efficient pathway for the conversion of methane and CO₂ into synthesis gas ready for the Fischer–Tropsch process, which largely depends on the redox behavior of oxygen carriers. Perovskite-structured metal oxides are promising candidates for CL-DRM due to the structural diversity brought about by elemental doping. Herein, we proposed to fabricate a highly active oxygen carrier via functionally designed Mn-based perovskite oxides via polymetallic doping. Cu-doping in the B-site of SrMnO_3−δ reveals a significant anti-coking effect in the high-temperature continuous CH₄/CO₂ redox process. Ni-doping in the B-site boosts the performance of methane activation resulting in high methane conversion. Moreover, Ce-doping in the A-site elevates oxygen migration and enhances partial oxidation of methane to H₂ and CO as well as the re-oxidation of reduced perovskite oxides. Considering the roles of Cu, Ni and Ce doping of SrMnO_3−δ, a polymetallic-doped perovskite of Sr_0.8Ce_0.2Mn_0.7Cu_0.1Ni_0.2O_3−δ was synthesized and evaluated in CL-DRM. The optimized perovskite oxide demonstrated exceptional performance with a methane conversion of 85% and a CO selectivity of 93% throughout 30 redox cycles at 850 °C. In the redox reactions, the transition metals of Mn, Cu, and Ni agglomerated during the reduction but could return to a well-dispersed state after re-oxidization with CO₂. The perovskite oxide exhibits self-structural-regenerability and the nano-scale agglomeration–dispersion cycle ensures the high structural stability of the material in the successive CL-DRM cycles. This study provides an important insight into the regulation of catalytic activity, oxygen mobility and carbon-resistance via doping of perovskite oxides with various kinds of compatible elements in both A and B sites.

The major obstacle in electrocatalytic seawater splitting (ESS) is the electro-oxidation of dissolved ions at the anode, which causes significant electrode corrosion and competes with the oxygen evolution reaction (OER), ultimately lowering efficiency. Although various electrocatalysts have been employed, achieving high current densities for seawater splitting without triggering side reactions remains a challenging task. Therefore, researchers have substituted oxygen evolution reaction (OER) in seawater electrolysis with various anodic oxidation reactions (AORs) including organic/inorganic compounds. This development of a hybrid seawater electrolysis system enhances hydrogen production at the cathode and generates high-value products at the anode. This approach is crucial in preventing side reactions like chloride oxidation reaction (ClOR), OER, and catalyst corrosion. In recent years, this technique has been extensively explored by researchers to address the challenges of seawater electrolysis and improve its efficiency. A series of electrocatalysts have been investigated for hybrid seawater electrolysis. Despite significant progress in this emerging area, there is no dedicated review available in the literature for hybrid seawater electrolysis. This review aims to fill this gap by focusing systematically on the recent progress and development of electrocatalysts specifically designed for hybrid seawater electrolysis. This review explores the structure–property–performance relationships of electrocatalysts, supported by pioneering examples. The impact of structure, morphology, and electronic properties of the catalysts on hybrid seawater electrolysis performance has been described in detail. Additionally, we discuss future advancements and challenges associated with the ongoing research into hybrid seawater electrolysis.

Copper stands at the forefront of materials driving the global transition to renewable energy and is a valued material for various important applications. For the first time, this paper presents an environmentally sustainable approach for recovering metallic copper through photocatalytic processes on a pilot scale, avoiding the energy-intensive conventional techniques. The study is focused on the selective photocatalytic reduction of copper(II) to either copper(I) or zerovalent copper (Cu(0)) based on the reaction conditions. This entire process does not involve strong acids or bases or any hazardous chemicals but needs only light and simple photocatalysts such as zinc oxide (ZnO) and poly(o-phenylenediamine)/zinc oxide (POPD/ZnO). A raceway pond reactor (RPR) was used to scale up the process in deionized water (DW), tap water (TW), and seawater (SW) using ZnO. Thermodynamic considerations were used to predict the reduction of Cu(II) to Cu(I) {Cu(II)/Cu(I) (+0.153 V)} and Cu(0){Cu(II)/Cu(0) (+0.337 V), Cu(I)/Cu(0) (+0.521 V)}. Formic acid served as a sacrificial reagent, while chloride ions modulated the reaction pathways and products at pH 6.5. The copper speciation of Cu(II), Cu(I), and Cu(0) was analyzed using X-ray diffraction (XRD), fluorescence spectroscopy (FS), laser-induced breakdown spectroscopy (LIBS), energy-dispersive X-ray spectroscopy (EDX), and flame atomic absorption spectroscopy (FAAS). The “first copper coin” was produced solely through 100% solar energy-driven photocatalysis. With an 80% recovery rate of Cu(0), our approach demonstrates a proof of concept for efficient copper recovery from wastewater, the mining industry, and e-waste. These findings offer valuable insights for further exploration of solar-driven metal recovery processes, underscoring the potential of solar energy in fostering sustainable industrial practices.

In this study, photoelectrochemical water oxidation with a hematite (α-Fe₂O₃) photoanode and electrochemical CO₂ reduction with a boron-doped diamond (BDD) cathode were combined to convert CO₂ into formic acid under 1 sun AM 1.5 simulated solar light irradiation. The faradaic efficiency of formic acid production by solar light-assisted CO₂ reduction reached 62% and the electrical-to-chemical energy conversion efficiency was 46%. The photo-assisted electrolysis efficiency reached 0.37%.