能源化学最新文献

The incorporation of partial A-site substitution in perovskite oxides represents a promising strategy for precisely controlling the electronic configuration and enhancing its intrinsic catalytic activity. Conventional methods for A-site substitution typically involve prolonged high-temperature processes. While these processes promote the development of unique nanostructures with highly exposed active sites, they often result in the uncontrolled configuration of introduced elements. Herein, we present a novel approach for synthesizing two-dimensional (2D) porous GdFeO₃ perovskite with A-site strontium (Sr) substitution utilizing microwave shock method. This technique enables precise control of the Sr content and simultaneous construction of 2D porous structures in one step, capitalizing on the advantages of rapid heating and cooling (temperature ∼1100 K, rate ∼70 K s⁻¹). The active sites of this oxygen-rich defect structure can be clearly revealed through the simulation of the electronic configuration and the comprehensive analysis of the crystal structure. For electrocatalytic oxygen evolution reaction application, the synthesized 2D porous Gd_0.8Sr_0.2FeO₃ electrocatalyst exhibits an exceptional overpotential of 294 mV at a current density of 10 mA cm⁻² and a small Tafel slope of 55.85 mV dec⁻¹ in alkaline electrolytes. This study offers a fresh perspective on designing crystal configurations and the construction of nanostructures in perovskite.

The global energy-related CO₂ emissions have rapidly increased as the world economy heavily relied on fossil fuels. This paper explores the pressing challenge of CO₂ emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO₂ (CO₂RR). The focus is on the development of robust and selective catalysts, particularly metal and metal-oxide-based materials. Porous metal oxides offer high surface area, enhancing the accessibility to active sites and improving reaction kinetics. The tunability of these materials allows for tailored catalytic behavior, targeting optimized reaction mechanisms for CO₂RR. The work also discusses the various synthesis strategies and identifies key structural and compositional features, addressing challenges like high overpotential, poor selectivity, and low stability. Based on these insights, we suggest avenues for future research on porous metal oxide materials for electrochemical CO₂ reduction.

The sluggish kinetics of the electrochemical oxygen reduction reaction (ORR) in intermediate-temperature solid oxide fuel cells (IT-SOFCs) greatly limits the overall cell performance. In this study, an efficient and durable cathode material for IT-SOFCs is designed based on density functional theory (DFT) calculations by co-doping with Nb and Ta the B-site of the SrFeO_3−δ perovskite oxide. The DFT calculations suggest that Nb/Ta co-doping can regulate the energy band of the parent SrFeO_3−δ and help electron transfer. In symmetrical cells, such cathode with a SrFe_0.8Nb_0.1Ta_0.1O_3−δ (SFNT) detailed formula achieves a low cathode polarization resistance of 0.147 Ω cm² at 650 °C. Electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) analysis confirm that the co-doping of Nb/Ta in SrFeO_3−δ B-site increases the balanced concentration of oxygen vacancies, enhancing the electrochemical performance when compared to 20 mol% Nb single-doped perovskite oxide. The cathode button cell with Ni-SDC|SDC|SFNT configuration achieves an outstanding peak power density of 1.3 W cm⁻² at 650 °C. Moreover, the button cell shows durability for 110 h under 0.65 V at 600 °C using wet H₂ as fuel.

Functional materials may change color by heat and electricity separately or simultaneously in smart windows. These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals' quality of life. Unfortunately, dual-responsive materials have not received ample research attention due to economic and technological challenges. As a consequence, the broader utilization of smart windows faces hindrances. To address this new generational multi-stimulus responsive chromic materials, our group has adopted a developmental strategy to create a poly(NIPAM)_n-HV as a switchable material by anchoring active viologen (HV) onto a phase-changing poly(NIPAM)_n-based smart material for better utility and activity. These constructed smart windows facilitate individualistic reversible switching, from a highly transparent state to an opaque state (thermochromic) and a red state (electrochromic), as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque (thermochromic) and orange (electrochromic) states. Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance. Each unique chromic mode operates independently and modulates visible and near-infrared (NIR) light in a distinct manner. Hence, these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities, rendering them highly attractive for applications in building facades, energy harvesting, privacy protection, and color display.

The interaction between metal and support is critical in oxygen catalysis as it governs the charge transfer between these two entities, influences the electronic structures of the supported metal, affects the adsorption energies of reaction intermediates, and ultimately impacts the catalytic performance. In this study, we discovered a unique charge transfer reversal phenomenon in a metal/carbon nanohybrid system. Specifically, electrons were transferred from the metal-based species to N-doped carbon, while the carbon support reciprocally donated electrons to the metal domain upon the introduction of nickel. This led to the exceptional electrocatalytic performances of the resulting Ni-Fe/Mo₂C@nitrogen-doped carbon catalyst, with a half-wave potential of 0.91 V towards oxygen reduction reaction (ORR) and a low overpotential of 290 mV at 10 mA cm⁻² towards oxygen evolution reaction (OER) under alkaline conditions. Additionally, the Fe-Ni/Mo₂C@carbon heterojunction catalyst demonstrated high specific capacity (794 mA h g_Zn⁻¹) and excellent cycling stability (200 h) in a Zn-air battery. Theoretical calculations revealed that Mo₂C effectively inhibited charge transfer from Fe to the support, while secondary doping of Ni induced a charge transfer reversal, resulting in electron accumulation in the Fe-Ni alloy region. This local electronic structure modulation significantly reduced energy barriers in the oxygen catalysis process, enhancing the catalytic efficiency of both ORR and OER. Consequently, our findings underscore the potential of manipulating charge transfer reversal between the metal and support as a promising strategy for developing highly-active and durable bi-functional oxygen electrodes.

Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction (ORR) electrocatalysts in metal-air batteries. However, the active sites in defective carbon are easily subjected to serious oxidation or hydroxylation during ORR or storage, leading to rapid degradation of activity. Herein, we design a van der Waals heterostructure comprised of vitamin C (VC) and defective carbon (DC) to not only boost the activity but also enhance the durability and storage stability of the DC-VC electrocatalyst. The formation of VC van der Waals between DC and VC is demonstrated to be an effective strategy to protect the defect active sites from oxidation and hydroxylation degradation, thus significantly enhancing the electrochemical durability and storage anti-aging performance. Moreover, the DC-VC van der Waals can reduce the reaction energy barrier to facilitate the ORR. These findings are also confirmed by operando Fourier transform infrared spectroscopy and density functional theory calculations. It is necessary to mention that the preparation of this DC-VC electrocatalyst can be scaled up, and the ORR performance of the largely produced electrocatalyst is demonstrated to be very consistent. Furthermore, the DC-VC-based aluminum-air batteries display very competitive power density with good performance maintenance.

Solving the problems of low electrical conductivity and poor cycling durability in transition metal oxides-based anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) has already turned into an urgent requirement. In this paper, we successfully synthesized Co₂VO₄/Co compounds with Co-V-MOF (metal-organic framework) as a sacrificial template and investigated their electrochemical mechanism in order to improve the electrochemical properties of LIBs and SIBs. The optimized heaping configuration and the existence of metallic Co catalyzed the formation of radical ions, thereby facilitating higher conductivity, shortening Li⁺ and Na⁺ transport paths, and providing more active sites. Co₂VO₄/Co constructed with 2-methylimidazole as a ligand showed a discharge capacity of 1605.1 mA h g⁻¹ after 300 cycles at 0.1 A g⁻¹ in LIB and 677.2 mA h g⁻¹ in SIB. Density functional theory (DFT) calculation emphasizes the crucial role of Co₂VO₄/Co in enhancing electrode conductivity, decreasing the migratory energy barrier, and thereby strengthening electrochemical properties. This heterostructure building technique may pave the way for the development of high-performance LIBs and SIBs. Furthermore, the problem of the low first-loop coulombic efficiency faced by transition metal oxides is improved.

The poor stability of RuO₂ electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers. To dramatically enhance the durability of RuO₂ to construct activity-stability trade-off model is full of significance but challenging. Herein, a single atom Zn stabilized RuO₂ with enriched oxygen vacancies (SA Zn-RuO₂) is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction (OER). Compared with commercial RuO₂, the enhanced Ru–O bond strength of SA Zn-RuO₂ by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru, while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation. Simultaneously, the optimized surrounding electronic structure of Ru sites in SA Zn-RuO₂ decreases the adsorption energies of OER intermediates to reduce the reaction barrier. As a result, the representative SA Zn-RuO₂ exhibits a low overpotential of 210 mV to achieve 10 mA cm⁻² and a greatly enhanced durability than commercial RuO₂. This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

High efficiency, cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems. The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies. Herein, we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction (OER) for alkaline electrolysis, which yields current density of 10 mA cm⁻² at an overpotential of 215 mV in 0.1 M KOH electrolyte. The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity. Raman spectra revealed that the catalyst underwent structure reconstruction during OER, evolving into oxyhydroxide, which was the active site proceeding OER in alkaline electrolyte. In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst. This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability. These findings provide promising strategies for the rational design of non-noble metal OER catalysts.

The electrochemical CO₂ reduction reaction (CO₂RR) to controllable chemicals is considered as a promising pathway to store intermittent renewable energy. Herein, a set of catalysts based on copper-nitrogen-doped carbon xerogel (Cu-N-C) are successfully developed varying the copper amount and the nature of the copper precursor, for the efficient CO₂RR. The electrocatalytic performance of Cu-N-C materials is assessed by a rotating ring-disc electrode (RRDE), technique still rarely explored for CO₂RR. For comparison, products are also characterized by online gas chromatography in a H-cell. The as-synthesized Cu-N-C catalysts are found to be active and highly CO selective at low overpotentials (from −0.6 to −0.8 V vs. RHE) in 0.1 M KHCO₃, while H₂ from the competitive water reduction appears at larger overpotentials (−0.9 V vs. RHE). The optimum copper acetate-derived catalyst containing Cu-N₄ moieties exhibits a CO₂-to-CO turnover frequency of 997 h⁻¹ at −0.9 V vs. RHE with a H₂/CO ratio of 1.8. These results demonstrate that RRDE configuration can be used as a feasible approach for identifying electrolysis products from CO₂RR.