Journal of Energy Chemistry最新文献

High-entropy materials have become high-activity electrocatalysis owing to their high-entropy effect and multiple active sites. Herein, we synthesize a series of carbon-supported nano high-entropy oxides (HEOs/C), specifically (PtFeCoNiCu)O/C, using a carbothermal shock (CTS) method for application as a cathode catalyst in direct borohydride fuel cells (DBFCs). The microstructure of the prepared catalysts was characterized by X-ray photoelectron spectroscopy, X-ray absorption fine structure, and transmission electron microscopy. The prepared (PtFeCoNiCu)O/C, with particle sizes ranging from 2 to 4 nm, demonstrates 3.94 transferred electrons towards the oxygen reduction reaction in an alkaline environment, resulting in a minimal H₂O₂ yield of 2.6%. Additionally, it exhibits a Tafel slope of 61 mV dec⁻¹, surpassing that of commercial Pt/C (82 mV dec⁻¹). Furthermore, after 40,000 cycles of cyclic voltammetry (CV) testing, the half-wave potential of (PtFeCoNiCu)O/C shows a positive shift of 3 mV, with no notable decline in the limiting current density. When (PtFeCoNiCu)O/C is used as a cathode catalyst in DBFCs, the DBFC achieves a maximum power density of 441 mW cm⁻² at 60 °C and sustains a cell voltage of approximately 0.73 V after 52 h at 30 °C. These findings confirm that HEO/C is a promising cathode catalyst for DBFCs.

Widely used spin-coated nickle oxide (NiO_x) based perovskite solar cells often suffer from severe interfacial reactions between the NiO_x and adjacent perovskite layers due to surface defect states, which inherently impair device performance in a long-term view, even with surface molecule passivation. In this study, we developed high-quality magnetron-sputtered NiO_x thin films through detailed process optimization, and compared systematically sputtered and spin-coated NiO_x thin film surfaces from materials to devices. These sputtered NiO_x films exhibit improved crystallinity, smoother surfaces, and significantly reduced Ni³⁺ or Ni vacancies compared to their spin-coated counterparts. Consequently, the interface between the perovskite and sputtered NiO_x film shows a substantially reduced density of defect states. Perovskite solar cells (PSCs) fabricated with our optimally sputtered NiO_x films achieved a high power conversion efficiency (PCE) of up to 19.93% and demonstrated enhanced stability, maintaining 86.2% efficiency during 500 h of maximum power point tracking under one standard sun illumination. Moreover, with the surface modification using (4-(2,7-dibromo-9,9-dimethylacridin-10(9H)-yl)butyl)phosphonic acid (DMAcPA), the device PCE was further promoted to 23.07%, which is the highest value reported for sputtered NiO_x based PSCs so far.

Organic solar cells (OSCs) hold great potential as a photovoltaic technology for practical applications. However, the traditional experimental trial-and-error method for designing and engineering OSCs can be complex, expensive, and time-consuming. Machine learning (ML) techniques enable the proficient extraction of information from datasets, allowing the development of realistic models that are capable of predicting the efficacy of materials with commendable accuracy. The PM6 donor has great potential for high-performance OSCs. However, it is crucial for the rational design of a ternary blend to accurately forecast the power conversion efficiency (PCE) of ternary OSCs (TOSCs) based on a PM6 donor. Accordingly, we collected the device parameters of PM6-based TOSCs and evaluated the feature importance of their molecule descriptors to develop predictive models. In this study, we used five different ML algorithms for analysis and prediction. For the analysis, the classification and regression tree provided different rules, heuristics, and patterns from the heterogeneous dataset. The random forest algorithm outperforms other prediction ML algorithms in predicting the output performance of PM6-based TOSCs. Finally, we validated the ML outcomes by fabricating PM6-based TOSCs. Our study presents a rapid strategy for assessing a high PCE while elucidating the substantial influence of diverse descriptors.

Zeolite nanosheets with a short b-axis thickness are highly desirable in lots of catalytic reactions due to their reduced diffusion resistance. Nevertheless, conventional synthesis methods usually require expensive structure-directing agents (SDAs), pricey raw materials, and eco-unfriendly fluorine-containing additives. Here, we contributed a cost-effective and fluoride-free synthesis method for synthesizing high-quality MFI zeolite nanosheets through a Silicalite-1 (Sil-1) seed suspension and urea cooperative strategy, only with inexpensive colloidal silica as the Si source. Our approach was effective for synthesizing both Sil-1 and aluminum-containing ZSM-5 nanosheets. By optimizing key synthesis parameters, including seed aging time, seed quantity, and urea concentration, we achieved precise control over the crystal face aspect ratio and b-axis thickness. We also revealed a non-classical oriented nanosheet growth mechanism, where Sil-1 seeds induced the formation of quasi-ordered precursor particles, and the (010) crystal planes of these particles facilitated urea adsorption, thereby promoting c-axis-oriented growth. The obtained ZSM-5 nanosheets exhibited exceptional catalytic performance in the benzene alkylation with ethanol, maintaining stability for over 500 h, which is 5 times longer than traditional ZSM-5 catalysts. Furthermore, large-scale production of ZSM-5 nanosheets was successfully carried out in a 3 L high-pressure autoclave, yielding samples consistent with those from laboratory-scale synthesis. This work marks a significant step forward in the sustainable and efficient production of MFI nanosheets using inexpensive and environmentally friendly raw materials, offering the broad applicability in catalysis.

Aqueous Zn-ion batteries (AZIBs) have received considerable attention owing to their various advantages such as safety, low cost, simple battery assembly conditions, and high ionic conductivity. However, they still suffer from serious problems, including uncontrollable dendrite growth, corrosion, hydrogen evolution reaction (HER) from water decomposition, electrode passivation, and unexpected by-products. The creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these issues. Herein, we propose the use of a perovskite CaTiO₃ (CTO) protective layer on Zn (CTO@Zn) as a promising approach for improving the performance of AZIBs. The CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant (ε_r = 180) and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn²⁺ ions in the CTO layer. By avoiding the direct contact of the Zn anode with the electrolyte solution, the uneven dendrite growth, corrosion, parasitic side reactions, and HER are mitigated, while CTO retains its mechanical and chemical robustness during cycling. Consequently, CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare Zn. CTO@Zn shows steady overpotential (∼68 mV) for 1500 h at 1 mA cm⁻²/0.5 mA h cm⁻², excelling bare Zn. Moreover, when paired with the V₂O₅-C cathode, the CTO@Zn//V₂O₅-C full battery delivers 148.4 mA h g⁻¹ (based on the mass of the cathode) after 300 cycles. This study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

Dual atomic catalysts (DAC), particularly copper (Cu₂)-based nitrogen (N) doped graphene, show great potential to effectively convert CO₂ and nitrate (NO₃⁻) into important industrial chemicals such as ethylene, glycol, acetamide, and urea through an efficient catalytical process that involves C–C and C–N coupling. However, the origin of the coupling activity remained unclear, which substantially hinders the rational design of Cu-based catalysts for the N-integrated CO₂ reduction reaction (CO₂RR). To address this challenge, this work performed advanced density functional theory calculations incorporating explicit solvation based on a Cu₂-based N-doped carbon (Cu₂N₆C₁₀) catalyst for CO₂RR. These calculations are aimed to gain insight into the reaction mechanisms for the synthesis of ethylene, acetamide, and urea via coupling in the interfacial reaction micro-environment. Due to the sluggishness of CO₂, the formation of a solvation electric layer by anions (F⁻, Cl⁻, Br⁻, and I⁻) and cations (Na⁺, Mg²⁺, K⁺, and Ca²⁺) leads to electron transfer towards the Cu surface. This process significantly accelerates the reduction of CO₂. These results reveal that *CO intermediates play a pivotal role in N-integrated CO₂RR. Remarkably, the Cu₂-based N-doped carbon catalyst examined in this study has demonstrated the most potential for C–N coupling to date. Our findings reveal that through the process of a condensation reaction between *CO and NH₂OH for urea synthesis, *NO₃⁻ is reduced to *NH₃, and *CO₂ to *CCO at dual Cu atom sites. This dual-site reduction facilitates the synthesis of acetamide through a nucleophilic reaction between NH₃ and the ketene intermediate. Furthermore, we found that the I⁻ and Mg²⁺ ions, influenced by pH, were highly effective for acetamide and ammonia synthesis, except when F⁻ and Ca²⁺ were present. Furthermore, the mechanisms of C–N bond formation were investigated via ab-initio molecular dynamics simulations, and we found that adjusting the micro-environment can change the dominant side reaction, shifting from hydrogen production in acidic conditions to water reduction in alkaline ones. This study introduces a novel approach using ion-H₂O cages to significantly enhance the efficiency of C–N coupling reactions.

Photocatalytic oxygen reduction for hydrogen peroxide (H₂O₂) synthesis presents a green and cost-effective production method. However, achieving highly selective H₂O₂ synthesis remains challenging, necessitating precise control over free radical reaction pathways and minimizing undesirable oxidative by-products. Herein, we report for the visible light-driven simultaneous co-photocatalytic reduction of O₂ to H₂O₂ and oxidation of biomass using the atomic rubidium-nitride modified carbon nitride (CNRb). The optimized CNRb catalyst demonstrates a record photoreduction rate of 8.01 mM h⁻¹ for H₂O₂ generation and photooxidation rate of 3.75 mM h⁻¹ for furfuryl alcohol to furoic acid, achieving a remarkable solar-to-chemical conversion (SCC) efficiency of up to 2.27%. Experimental characterizations and DFT calculation disclosed that the introducing atomic Rb–N configurations allows for the high-selective generation of superoxide radicals while suppressing hydroxyl free radical formation. This is because the Rb–N serves as the new alternative site to perceive a stronger connection position for O₂ adsorption and reinforce the capability to extract protons, thereby triggering a high selective redox product formation. This study holds great potential in precisely regulating reactive radical processes at the atomic level, thereby paving the way for efficient synthesis of H₂O₂ coupled with biomass valorization.

Proton exchange membrane fuel cells (PEMFCs) provide an appealing sustainable energy system, with the solid-electrolyte membrane playing a crucial role in its overall performance. Currently, sulfonated poly(1,4-phenylene ether-ether sulfone) (SPEES), an aromatic hydrocarbon polymer, has garnered considerable attention as an alternative to Nafion polymers. However, the long-term durability and stability of SPEES present a significant challenge. In this context, we introduce a potential solution in the form of an additive, specifically a core–shell-based amine-functionalized iron titanate (A–Fe₂TiO₅), which holds promise for improving the lifetime, proton conductivity, and power density of SPEES in PEMFCs. The modified SPEES/A–Fe₂TiO₅ composite membranes exhibited notable characteristics, including high water uptake, enhanced thermomechanical stability, and oxidative stability. Notably, the SPEES membrane loaded with 1.2 wt% of A–Fe₂TiO₅ demonstrates a maximum proton conductivity of 155 mS cm⁻¹, a twofold increase compared to the SPEES membrane, at 80 °C under 100% relative humidity (RH). Furthermore, the 1.2 wt% of A–Fe₂TiO₅/SPEES composite membranes exhibited a maximum power density of 397.37 mW cm⁻² and a current density of 1148 mA cm⁻² at 60 °C under 100% RH, with an open-circuit voltage decay of 0.05 mV/h during 103 h of continuous operation. This study offers significant insights into the development and understanding of innovative SPEES nanocomposite membranes for PEMFC applications.

Transition metal-based nanomaterials have emerged as promising electrocatalysts for oxygen evolution reaction (OER). Considerable research efforts have shown that self-reconstruction occurs on these nanomaterials under operating conditions of OER process. However, most of them undergo incomplete reconstruction with limited thickness of reconstruction layer, leading to low component utilization and arduous exploration of real catalytic mechanism. Herein, we identify the dynamic behaviors in complete reconstruction of Co-based complexes during OER. The hollow phytic acid (PA) cross-linked CoFe-based complex nanoboxes with porous nanowalls are designed because of their good electrolyte penetration and mass transport ability, in favor of the fast and complete reconstruction. A series of experiment characterizations demonstrate that the reconstruction process includes the fast substitution of PA by OH⁻ to form Co(Fe)(OH)_x and subsequent potential-driven oxidation to Co(Fe)OOH. The obtained CoFeOOH delivers a low overpotential of 290 mV at a current density of 10 mA cm⁻² and a long-term stability. The experiment results together with theory calculations reveal that the Fe incorporation can result in the electron rearrangement of reconstructed CoFeOOH and optimization of their electronic structure, accounting for the enhanced OER activity. The work provides new insights into complete reconstruction of metal-based complexes during OER and offers guidelines for rational design of high-performance electrocatalysts.

The kinetic characteristics of plasma-assisted oxidative pyrolysis of ammonia are studied by using the global/fluid models hybrid solution method. Firstly, the stable products of plasma-assisted oxidative pyrolysis of ammonia are measured. The results show that the consumption of NH₃/O₂ and the production of N₂/H₂ change linearly with the increase of voltage, which indicates the decoupling of non-equilibrium molecular excitation and oxidative pyrolysis of ammonia at low temperatures. Secondly, the detailed reaction kinetics mechanism of ammonia oxidative pyrolysis stimulated by a nanosecond pulse voltage at low pressure and room temperature is established. Based on the reaction path analysis, the simplified mechanism is obtained. The detailed and simplified mechanism simulation results are compared with experimental data to verify the accuracy of the simplified mechanism. Finally, based on the simplified mechanism, the fluid model of ammonia oxidative pyrolysis stimulated by the nanosecond pulse plasma is established to study the pre-sheath/sheath behavior and the resultant consumption and formation of key species. The results show that the generation, development, and propagation of the pre-sheath have a great influence on the formation and consumption of species. The consumption of NH₃ by the cathode pre-sheath is greater than that by the anode pre-sheath, but the opposite is true for OH and O(¹S). However, within the sheath, almost all reactions do not occur. Further, by changing the parameters of nanosecond pulse power supply voltage, it is found that the electron number density, electron current density, and applied peak voltages are not the direct reasons for the structural changes of the sheath and pre-sheath. Furthermore, the discharge interval has little effect on the sheath structure and gas mixture breakdown. The research results of this paper not only help to understand the kinetic promotion of non-equilibrium excitation in the process of oxidative pyrolysis but also help to explore the influence of transport and chemical reaction kinetics on the oxidative pyrolysis of ammonia.