ACS Applied Energy Materials最新文献

The transition to a hydrogen-based economy necessitates the development of safe, cost-effective hydrogen storage media at an industrial scale. The equiatomic intermetallic titanium–iron (TiFe) alloy is a prime candidate for stationary hydrogen applications due to its high volumetric storage density, nontoxicity, and safety attributes. However, the conventional synthesis of TiFe alloy relies on high purity titanium and iron metal feedstocks, which must first be extracted from their respective ores before being alloyed in equiatomic ratio. This is a complex, multistep process posing environmental and economic challenges associated with the extraction of metallurgical-grade titanium. Here, we propose an alternate straightforward synthesis pathway for TiFe alloy through the direct calciothermic reduction of ilmenite sand (FeTiO₃). Initial small-scale experiments have achieved a maximum TiFe yield of approximately 52 wt %, with similar yields observed when scaling up to 100 g samples. The TiFe alloy produced via this pathway demonstrated a hydrogen storage capacity of approximately 0.71 wt % after activation at 65 bar, indicating that direct metallothermic reduction of ilmenite sand represents an attractive alternative production route for hydrogen storage alloys, which offers economic and sustainability advantages over the existing industrial pathway.

Two organic molecules, TPA-2Th and TPA-2Py, are developed and serve as self-assembled monolayers (SAMs) for Sb₂(S,Se)₃ (antimony selenosulfide) solar cells. The solid interface interaction between SAMs and Sb₂(S,Se)₃ accomplishes suppressed surface defects, uniform surface potential, suitable interfacial band-bending alignment, efficient charge transfer, and improved photoelectric properties. The optimized solar cells with SAMs show increased power conversion efficiencies (PCEs). For TPA-2Th, the champion PCE is inspiringly enhanced by >10% to 8.21%. This is the first time novel SAMs have been developed specifically for Sb₂(S,Se)₃ solar cells, and this will bring fresh strategies for improving Sb-based solar cells.

In order to increase the energy density and improve the cyclability of lithium-sulfur (Li-S) batteries, a combined strategy is devised and evaluated for high-performance Li-S batteries. It consists of the following steps to reduce the loss of active sulfur and sulfides migrating in the liquid electrolyte to the anode and add electrocatalyst groups in the cathode or catholyte: (i) A hollow porous nanoparticle coating cathode host with a pseudocapacitive PEDOT:PSS binder that also contributes to trapping polysulfides. (ii) A thin interlayer of B-N-graphene (BNG) nanoplatelets on the above cathode trapping polysulfides while participating in the electron transfer and acting as an electrocatalyst, thus ensuring that the trapped sulfides remain active in the cathode. (iii) Added semiconductor phthalocyanine VOPc or CoPc to form an electrocatalyst network in the catholyte, trapping polysulfides and promoting their redox reactions with Li⁺ ions. (iv) Added silk fibroin in the liquid electrolyte, which also suppresses dendritic growth on the lithium anode. This strategy is evaluated step-by-step in Li-S battery cells characterized experimentally and in simulations based on a multipore continuum physicochemical model with adsorption energy data supplied from molecular dynamics simulations. The thin BNG interlayer sprayed on the cathode proved a decisive factor in improving cell performance in all cases. A Li-S cell combining features from (i), (ii), and (iv) and with 45 wt % S in the cathode yields 1372 mAh g_S ^-1 at first discharge and 920 mAh g_S ^-1 at the 100th discharge after a cycling schedule at different C-rates. A Li-S cell combining features from (i), (ii), and (iii) and with 55 wt % S in the cathode yields 805 and 586 mAh g_S ^-1 at the first and the 100th discharge, respectively.

The oxygen evolution reaction (OER) is of utmost importance for the electrochemical water splitting process that is imperative for hydrogen generation without a carbon footprint. Though high overpotential and lower faradaic efficiency are integrated problems with the OER, recent studies manifest that introducing a spin-polarization improvement of the OER is feasible over the thermodynamic limit of the catalyst. Conceiving this idea, here, we demonstrate the superior electrochemical performance of electrochemically deposited amorphous chiral iron-doped cobalt oxide that exhibits higher current density and lower Tafel slope compared with its achiral analogue. Furthermore, we address a solution for another associated problem of the OER, i.e., hydrogen peroxide production as a byproduct, by illustrating the reduction of the hydrogen peroxide yield using the chiral catalyst. A detailed study proposes that the observed outcomes are attributed to the formation of a spin-polarized intermediate, which originates from the chirality-induced spin selectivity effect.

Aliovalent-doped BaF₂ exhibits high ionic conductivity, making it a promising candidate as a solid electrolyte in high-energy-density fluoride-ion batteries. When Ba²⁺ is partially substituted with trivalent ions, such as La³⁺ or Bi³⁺, the introduction of additional fluorine yielded for the sake of the charge neutralization condition increases the conductivity by 4 orders of magnitude, reaching approximately 10^–4 S cm^–1 at 150 °C. However, the relationship between the position of the additional fluorine within the crystal structure and the electrical properties remains unclear. In this study, we explore it by varying the aliovalent dopants in the mechanochemically synthesized Ba_0.57M_0.43F_2.43 (M = Y, La, Nd, Sm, Bi) and investigating both the electrical properties and the structures. For these aliovalent-doped compounds, improved conductivity is observed, and for certain compounds, the electrochemical stability window extends beyond 5.5 V. We perform Rietveld refinement of neutron powder diffraction data and the maximum entropy method to investigate the fluorine positions. These crystal structures suggest the fluorine positions deviated from the ideal octahedral center 4b to the combinations of 24e, 32f, and 48i positions in the cubic BaF₂ crystal (space group Fm3̅m) to form a closer ionic conduction path.

In order to increase the energy density and improve the cyclability of lithium–sulfur (Li–S) batteries, a combined strategy is devised and evaluated for high-performance Li–S batteries. It consists of the following steps to reduce the loss of active sulfur and sulfides migrating in the liquid electrolyte to the anode and add electrocatalyst groups in the cathode or catholyte: (i) A hollow porous nanoparticle coating cathode host with a pseudocapacitive PEDOT:PSS binder that also contributes to trapping polysulfides. (ii) A thin interlayer of B–N-graphene (BNG) nanoplatelets on the above cathode trapping polysulfides while participating in the electron transfer and acting as an electrocatalyst, thus ensuring that the trapped sulfides remain active in the cathode. (iii) Added semiconductor phthalocyanine VOPc or CoPc to form an electrocatalyst network in the catholyte, trapping polysulfides and promoting their redox reactions with Li⁺ ions. (iv) Added silk fibroin in the liquid electrolyte, which also suppresses dendritic growth on the lithium anode. This strategy is evaluated step-by-step in Li–S battery cells characterized experimentally and in simulations based on a multipore continuum physicochemical model with adsorption energy data supplied from molecular dynamics simulations. The thin BNG interlayer sprayed on the cathode proved a decisive factor in improving cell performance in all cases. A Li–S cell combining features from (i), (ii), and (iv) and with 45 wt % S in the cathode yields 1372 mAh g_S^–1 at first discharge and 920 mAh g_S^–1 at the 100th discharge after a cycling schedule at different C-rates. A Li–S cell combining features from (i), (ii), and (iii) and with 55 wt % S in the cathode yields 805 and 586 mAh g_S^–1 at the first and the 100th discharge, respectively.

Designing materials with a controlled photovoltaic response may lead to improved solar cells or photosensors. In this regard, ferroelectric superlattices have emerged as a rich platform to engineer functional properties. In addition, ferroelectrics are naturally endowed with a bulk photovoltaic response stemming from nonthermalized photoexcited carriers, which can overcome the fundamental limits of current solar cells. Yet, their photovoltaic output has been limited by poor optical absorption and poor charge collection or photoexcited carrier mean free path. We use Density Functional Theory and Wannierization to compute the so-called Bulk Photovoltaic shift current and the optical properties of BiFeO₃/LaFeO₃ superlattices. We show that, by stacking these two materials, not only the optical absorption is improved at larger wavelengths (due to LaFeO₃ smaller bandgap) but also the photogalvanic shift current is enhanced compared to that of pure BiFeO₃, by suppressing the destructive interferences occurring between different wavelengths.

CuI is a well-known thermoelectric (TE) material recognized for its p-type characteristics. However, the development of its n-type counterpart and the integration of both p- and n-type CuI in thermoelectric generators (TEGs) remain largely unexplored. In this study, we successfully tuned the thermoelectric properties of CuI by strategically incorporating Ag, enabling the synthesis of both p-type (Ag_0.2Cu_0.8I) and n-type (Ag_0.9Cu_0.1I) materials using a cost-effective, greener, and scalable successive ionic layer adsorption and reaction (SILAR) method. The p-type Ag_0.2Cu_0.8I exhibited a figure of merit (ZT) of 0.47 at 340 K, driven by a high Seebeck coefficient of 810 μV·K^-1. In contrast, the n-type Ag_0.9Cu_0.1I achieved an exceptional ZT of 2.5 at 340 K, attributed to an ultrahigh Seebeck coefficient of -1891 μV·K^-1. These superior thermoelectric properties make CuI-based materials attractive alternatives to conventional TE materials, such as Bi₂Te₃ and PbTe, which are limited by toxicity and resource scarcity. Furthermore, a prototype thermoelectric glazing unit (5 × 5 cm²) demonstrated a 14 K temperature differential, highlighting its dual functionality in power generation and building heat loss mitigation. These findings underscore the potential of low-cost CuI-based materials for advancing sustainable energy technologies.

Zinc-ion batteries have emerged as promising candidates for large-scale energy storage applications due to their low cost and high safety. However, the growth of zinc dendrites during Zn²⁺ deposition remains a critical obstacle to their commercialization. In this work, we first screened a more zincophilic MAX-phase material, Ti₂AlC, through theoretical calculations of various common MAX-phase materials, and then developed a three-dimensional (3D) Ti₂AlC MAX-phase coating on zinc metal (denoted as 3D-Ti₂AlC@Zn) as an artificial intermediate phase to regulate the distribution of Zn²⁺ during plating/stripping. The MAX phase provides abundant active sites that attract Zn²⁺, while its 3D porous conductive network promotes uniform zinc deposition and suppresses dendrite formation, leading to enhanced cycling stability in aqueous zinc-ion batteries. Benefiting from the protective 3D-Ti₂AlC coating, the symmetric cell exhibits an extended lifespan of over 1800 h at 1 mA/cm². Moreover, full cells with MnO₂ cathodes achieve higher specific capacity and improved stability compared to those using bare zinc anodes when they are operated at 2 A/g. This approach offers a viable strategy for developing durable zinc anodes, potentially accelerating the application of zinc-ion batteries in energy storage systems.

During high current operation, substantial heterogeneity develops within battery cathodes, particularly when their thickness is large. Heterogeneity relaxation during subsequent rest is important for understanding battery performance under pulsed conditions. Localized charge balancing phenomena within batteries at zero net current are not well understood and merit investigation. In this work, the heterogeneity within cathodes of commercial alkaline Zn–MnO₂ batteries is measured during discharge and monitored during rest using energy dispersive X-ray diffraction (EDXRD). Significant gradients in protonation form during discharge and partially relax under rest. It is demonstrated that the proton gradient relaxation is through local redox activity at zero net current, where local (de)protonation works to redistribute charge across the cathode thickness. To support this redox-based relaxation, a fundamental kinetic study on prismatic MnO₂ cathodes is conducted to determine an appropriate model to describe both discharge and charge kinetics of MnO₂. These kinetics are incorporated into a computational model to simulate the proton gradient formation and partial relaxation under identical discharge conditions as the operando EDXRD experiments. Model and experimental data are found to be in excellent agreement, correctly predicting localized charge balancing at rest.