ACS Applied Energy Materials最新文献

Two sets of high-quality epitaxial ruthenium oxide (RuO₂) thin films with different thicknesses were synthesized in situ on cost-competitive sapphire substrates by using a pulsed laser deposition technique. The first set of films, with a thickness of 40 nm and a sheet resistance of 15.7 Ω/□, was prepared using 2100 laser pulses, while the second set of films, with a thickness of 87 nm and a sheet resistance of 6.7 Ω/□, was prepared using 4800 laser pulses. All other deposition parameters were kept the same. The post-deposition structural and morphological measurements showed that both sets of films grew at the same growth rate, had the same crystallinity, similar grain boundary density, and slightly different surface roughness. The thicker RuO₂ films achieved an overpotential of 280 mV for the oxygen evolution reaction at a current density of 100 μA/cm², comparable to or exceeding the performance of films grown on more expensive substrates. Comparatively, the thinner RuO₂ films, which have a significantly higher charge transfer resistance (250 Ω versus 100 Ω for thick films), display a higher overpotential of 320 mV. These results indicate that the lower electrical resistance of thicker films promotes charge transfer through the film body, leading to superior electrocatalytic properties.

A single lithium-ion conductive poly(lithium borate ester) water-soluble binder (PAA-MBLi) was utilized in the graphite anode with the motive of tuning the solid electrolyte interphase (SEI) and enhancing the ionic conductivity. The prelithiated binder and the boron-functionalized SEI enhanced the Li-ion kinetics with a low SEI and charge-transfer resistance, low activation energy, and a high diffusion coefficient. These enhancements enabled fast charging with a discharge capacity of 72 mAh/g at 5C and a capacity retention of 82.9% after 1400 cycles. The anodic half cells with PAA-MBLi exhibited a capacity retention of 80.4% after 750 cycles at 1C with a maximum capacity of 323 mAh/g. It also showed a 95.8% capacity retention after 100 cycles with a high mass loading of 5.55 mg/cm² at 0.2C and an appreciable initial Coulombic efficiency of 83.9%, indicating a thin SEI with minimum irreversible capacity loss. The PAA-MBLi binder exhibited a remarkable ionic conductivity of 8.160 × 10^–5 S cm^–1 and a high lithium transference number of 0.831 at 25 °C. The PAA-MBLi binder is also expected to reduce HF formation in the cell by consuming the fluoride ions and forming a B–F bond in the SEI, as indicated by the X-ray photoelectron spectroscopy spectra.

Organic solar cells (OSCs) have undergone rapid development over the past few decades owing to their high efficiency, mechanical flexibility, and potential for low-cost large-scale fabrication. Machine learning (ML) models capable of accurately predicting the power conversion efficiency (PCE) of OSCs can greatly accelerate the discovery of high-performance donor and acceptor materials. In this work, we developed ML models for PCE prediction by introducing a set of complementary molecular descriptors and performing a comprehensive descriptor selection. The resulting models achieved the highest test set R² value of 0.82 and average R² value of 0.76 on an updated mixed experimental data set, representing one of the best accuracies reported to date for OSC PCE prediction. Validation using published experimental data confirmed the model’s strong predictive accuracy and generalizability. Our results highlight that the proposed OPT3D descriptors effectively complement the structural information missing from RDKit and Morgan fingerprint descriptors. This study demonstrates that the development of complementary molecular descriptors is critical for improving ML model accuracy in molecular material research and provides a promising approach for the rational design of high-efficiency OSC materials.

Lithium-ion batteries (LIBs) are widely used due to their high cyclability and stability. However, the high cost of raw materials has spurred interest in sodium-ion batteries (SIBs) as a cost-effective alternative. Despite this, SIBs suffer from lower energy density and poorer cyclability, leaving them in a developmental stage. The formation of the solid electrolyte interphase (SEI) is critical for battery performance as it stabilizes the electrode and prevents further solvent degradation during cycling. This study investigated the SEI formation mechanism in sodium-based EC/DEC electrolyte by monitoring the evolution of volatile products and comparing them with those in lithium-based electrolytes under Ar and O₂ atmospheres using online electrochemical mass spectrometry and vibrational spectroscopy. It was demonstrated that the SEI forms via similar reaction pathways in both sodium- and lithium-based electrolytes. However, Na⁺ lead to more significant ethylene (C₂H₄) evolution during this process. Upon introducing O₂ into the operating environment, carbon dioxide (CO₂) and water were produced during the initial cycle. At the same time, the amount of C₂H₄ evolved was significantly lower than under Ar. The results indicate that in the presence of O₂, the superoxide (O₂^–) generated during the oxygen reduction reaction (ORR) alters the decomposition of EC molecules into two pathways. Because O₂^– is more stable in sodium-based electrolytes, a larger fraction of O₂^– participates in the decomposition of EC. This alters the electrochemical reduction reaction (ERR) pathway of C₂H₄ generated from EC decomposition to an ORR pathway that yields CO₂. We also found that specific additives, such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC), can improve SEI stability in SIBs by inhibiting solvent decomposition and promoting the formation of a denser, stronger SEI. These findings provide valuable insights into the development of stable SEI, particularly for advancing the performance of SIBs.

The wittichenite-type compound (Cu₃BiS₃, CBS) shows great potential for photovoltaic and solar-to-fuel applications due to its favorable optoelectronic properties. However, precise control over composition and phase stability in thin films remains challenging to achieve due to phase complexity and a limited kinetic stability window. This research focuses on obtaining homogeneous and stable CBS phases with ideal composition through a simple sulfurization process of an oxide Cu–Bi–O (CBO) precursor film in the thermodynamically permissible temperature range (350–425 °C). The findings confirm successful conversion of oxide film to the wittichenite phase, free of secondary phases, at 350 °C with a direct bandgap energy of 1.61 eV. The energy band positions from photoelectron spectroscopy show favorable energetics toward water splitting and CO₂ reduction. Photoelectrochemical performance of a prototype CBS/TiO₂ heterojunction device demonstrates a photocurrent density of 0.12 mA/cm² and 0.96 mA/cm² for water splitting and CO₂ reduction, respectively. The presented method can be further explored to fabricate CBS films in various configurations for PEC and solar cell devices.

Aqueous zinc-based batteries (AZBs) are considered promising for grid-scale energy storage owing to their low cost, safety, and eco-friendliness. The practical applications, however, are limited by zinc dendrite growth and parasitic side reactions at the anode. This work presents a strategy of employing glucose as an electrolyte additive to tailor the Zn²⁺ solvation environment. This modification successfully suppresses dendrite growth and improves the electrochemical reversibility of Zn plating/stripping. Mechanistically, glucose disrupts the hydrogen-bond network among water molecules and attenuates the hydration of Zn²⁺, leading to an optimized solvation structure. The electrolyte with 150 mM glucose, Zn||Cu cells achieve a high Coulombic efficiency of 98.8% and sustain 450 stable cycles at 1 mA cm^–2. Correspondingly, Zn||Zn symmetric cells exhibit dendrite-free operation for over 1050 h with a low overpotential of 40 mV. Furthermore, Zn||V₂O₅ full cells deliver outstanding cycling stability, retaining a capacity of 68 mAh g^–1 after 1000 cycles at 1C. This study offers a general and effective additive approach for developing advanced electrolytes in aqueous ZIBs.

1T–2H MoSe₂ was grown in situ on Ti₃C₂T_x MXene to develop a Pt-free HER electrocatalyst with enhanced interfacial charge transfer. The optimized composite delivers an overpotential of 68 mV at 10 mA cm^–2 and a Tafel slope of 74 mV dec^–1, along with excellent cycling stability of over 1000 cycles, showing negligible decay. The composite has an increased metallic 1T content and suppressed Mo⁶⁺ surface oxides. Electrochemical measurements reveal a substantially reduced charge-transfer resistance (R_ct ∼ 31 Ω) and a large ECSA (C_dl = 22.6 mF cm^–2). The catalyst showed improved activity, high TOF values, and a hydrogen-coverage profile consistent with a Volmer–Tafel pathway.

This study functionalizes MXene surfaces using silane coupling agents to prepare organo-MXene (MX-C═C, MX-NH₂, MX-NHC) with distinct functional groups (C═C, NH₂, NHC), which are further in situ composited with bimetallic metal–organic frameworks (Ni, Co-MOF) to develop NiCo-MOF@organo-MX composite electrode materials. Structural characterizations confirm that the functionalization effectively alleviates MXene sheet stacking and regulates the morphology and distribution density of MOF particles. Electrochemical tests reveal that NiCo-MOF@MX-NHC exhibits optimal performance, achieving a specific capacitance of 1682.6 F g^–1 at 1 A g^–1 and retaining 68% capacity after 5000 cycles at 20 A g^–1. The NH–CH₃ functional group enhances pseudocapacitive behavior and charge transfer efficiency by modulating MXene surface active site density and MOF dispersion. Furthermore, an asymmetric supercapacitor assembled with tetraethylammonium tetrafluoroborate/acetonitrile (TEMA-BF₄/AN) organic electrolyte demonstrates a wide voltage window of 2.4 V, delivering a high energy density of 41.5 Wh kg^–1 at 24,000 W kg^–1 power density, while successfully powering LED devices, validating its practical potential. This work provides theoretical and technical foundations for designing high-performance MOF@MXene composite electrodes.

The structure of biomass precursors plays an important role in determining the structure of hard carbon. However, the effects of biomass structures on the closed pore sodium storage performance of the resultant hard carbon have yet to be explored comprehensively. As this limitation has hindered the progress of high-capacity hard carbon anodes, three types of starch samples with varying amylopectin contents─namely, amylopectin, corn starch, and high-amylose starch─were selected in this study to prepare hard carbon microspheres as anodes in sodium-ion batteries. Amylopectin, composed of both α-1,6 and α-1,4 glycosidic bonds, contains more hydroxyl groups than amylose. Starch with a high amylopectin content generates more C═O and C═C bonds through dehydration during stabilization, facilitating chain cross-linking. This cross-linking effect creates narrow and long graphite microcrystalline structures, leading to the formation of large closed pores during carbonization. The hard carbon microspheres derived from the precursor with a high amylopectin content exhibit a higher closed-pore area of 519 m² g^–1, resulting in a higher reversible specific capacity of 333.2 mAh g^–1 and remarkable cycling stability. This study reveals the structure–function relationship between the amylopectin content and closed pore formation in hard carbon, providing valuable insights into the future application of starch-based carbon in sodium-ion batteries.

NaCl contamination of membrane-electrode assemblies is a critical challenge for the stability and long-term durability of proton-exchange membrane fuel cells (PEMFCs), particularly in marine and humid environments. In this study, we systematically investigated the degradation behavior of PEMFCs under NaCl exposure by decoupling the individual effects of Na⁺ and Cl^– ions through electrochemical and spectroscopic analyses. Electrochemical impedance spectroscopy revealed that Na⁺ had a minimal impact on proton conductivity, as evidenced by the stable ohmic resistance over time. In contrast, Cl^– significantly increased the charge transfer resistance and decreased the electrochemically active surface area, indicating strong catalyst poisoning. X-ray photoemission spectroscopy analysis showed broadened Pt 4f peaks and the emergence of Pt⁴⁺ states, while white X-ray absorption near-edge spectroscopy revealed an increase in the white-line intensity, reflecting the changes in electronic structure at the Pt surface. Transmission electron microscopy further confirmed the Pt nanoparticle growth from 2.4 to 4.0 nm after prolonged operation in both NaCl-free and NaCl-containing cells, which is consistent with Ostwald ripening rather than Cl^–-induced dissolution. Collectively, these results demonstrate that Na⁺ has a limited effect on membrane properties, while Cl^– interacts strongly with the catalyst. This study offers a systematic multimodal analysis of salt-induced failure modes in PEMFCs and provides critical insights into their deployment in chloride-rich environments.