ACS Energy Letters 最新文献

Fe-based O3-type Na-layered oxides such as Na[Ni_1/3Fe_1/3Mn_1/3]O₂ are attractive cathodes based on earth-abundant elements, yet their high-voltage operation is limited by voltage decay and capacity fading. Here, we identify a distortion−migration cascade initiated by Fe³⁺ oxidation to Fe⁴⁺. The resulting Jahn−Teller distortion of FeO₆ octahedra destabilizes Fe within the transition-metal (TM) framework. This destabilization promotes Fe migration into the Na layer and drives irreversible layered to rocksalt-like reconstruction. A stepwise strategy that reduces the Fe content, reinforces the TM−O framework, and blocks Fe migration into the Na layer interrupts this cascade. The optimized cathode delivers 177.96 mAh g⁻¹ with an initial Coulombic efficiency of 94.1% and retains 73.5% capacity after 100 cycles. Experimental and computational analyses reveal continuous structural evolution and suppressed Fe migration. These results establish suppression of distortion-driven Fe migration as a key design principle for stabilizing high-voltage operation in Fe-based Na-layered cathodes.

Resolving the long-standing trade-off between effective interfacial passivation and efficient charge transport remains a central challenge for perovskite/silicon tandem solar cells, particularly at the perovskite/C₆₀ interface. Here, inspired by the bio-isostere concept, we introduce a dipolar cage strategy that replaces traditional planar phenyl motifs with a rigid bicyclo[2.2.2]octane (BCO) scaffold. Distinct from conventional passivators relying solely on steric shielding, the BCO framework imparts a substantial intrinsic molecular dipole. This architecture establishes a favorable interfacial electrostatic field, substantially reducing the interfacial energetic mismatch for electron extraction while effectively suppressing nonradiative recombination. Utilizing bicyclo[2.2.2]octane-1,4-diammonium diiodide (BCODAI), monolithic perovskite/tunnel oxide passivated contact (TOPCon) tandem solar cells achieve a certified champion efficiency of 32.54%. Crucially, the devices exhibit outstanding operational stability, retaining over 80% of their initial efficiency after 1100 h of continuous operation. This dipolar-steric cage design provides an effective interfacial engineering principle for high-performance tandem photovoltaics.

Utilizing π-conjugated ligands offers opportunities to ameliorate intermolecular interactions between spacer cations, improving charge transport in 2D perovskites. We develop two new ligands by incorporating phenoxazine (PXZ) or phenothiazine (PTZ) moieties, namely PXZEAI and PTZEAI, in which oxygen-to-sulfur substitution induces the intrinsically coupled effects of a more folded conformation (17° smaller dihedral angle) and interfacial chemistry. Unexpectedly, X-ray diffraction (XRD) analysis exhibits distinct lattice spacings in (PTZEA)₂PbI₄ (16.81 Å) and (PXZEA)₂PbI₄ (20.36 Å). Density functional theory simulations and synchrotron radiation single-crystal XRD reveal closer packing for (PTZEA)₂PbI₄, consistent with stronger intermolecular π–π interaction enabled by a more folded conformation, together with sulfur-specific interfacial effects. Grazing incidence wide-angle X-ray scattering results further support π–π interactions between PTZEA⁺ cations. Ultimately, a contrasting efficiency trend is observed in 2D/3D perovskite solar cells (PTZEAI (25.28%) > control (23.18%) > PXZEAI (19.08%)). This performance difference reflects the synergy of heteroatom-driven conformational change and sulfur-mediated interfacial effects.

Platinum cocatalysts are essential for photocatalytic hydrogen evolution by organic semiconductor (OSC) bulk-heterojunction nanoparticles (BHJ NPs), yet the surface chemistry of photodeposited Pt remains poorly understood. Here, we show that the halide ligand in hexahaloplatinate(IV) precursors (K₂PtX₆, X = Cl, Br, I) critically governs both the kinetics of Pt photodeposition and the resulting photocatalytic performance. Chloroplatinate precursors leave partially reduced [PtCl_x]ⁿ species adsorbed on the Pt surface, poisoning active sites and severely suppressing H₂ evolution rates in BHJ systems that generate low photopotential, which is confirmed by photoelectrochemical measurements and Kelvin-probe force microscopy. Bromo- and iodoplatinate precursors reduce more readily, largely avoiding this poisoning. Remarkably, the addition of iodide ions to the photocatalytic mixture provides a substantial and general boost to H₂ evolution rates, reaching an apparent quantum yield of 17% at 700 nm (among the highest reported for BHJ NP photocatalysts) attributed to beneficial iodide adsorption on the Pt surface.

Poly(benzodifurandione) (PBFDO) is a promising n-type mixed conductor for organic electrochemical transistors (OECTs), but its high intrinsic conductivity results in excessive operating currents and energy consumption for neuromorphic computing. Here, we combine molecular-weight engineering and ionic doping to overcome this limitation. Benzofuranone end-capping produces a reduced chain length polymer (PBFDO-BF) with substantially lower intrinsic conductivity, while LiTFSI doping enhances ion-mediated conductance modulation and synaptic functionality. PBFDO-BF + LiTFSI provides enhanced OECT modulation and spike-dependent plasticity while reducing operating currents by approximately 1 order of magnitude compared with pristine PBFDO. In the Modified National Institute of Standards and Technology (MNIST)-based convolutional neural network simulations, the device achieves 97.8% training and 98.6% inference accuracy, with the lowest cumulative energy consumption to reach ≈90% accuracy. These results establish molecular-weight control combined with ionic doping as an effective strategy for developing energy-efficient PBFDO-based neuromorphic OECTs without compromising stability or solution processability.

While perovskite solar cells (PSCs) have garnered substantial attention owing to the high power conversion efficiency (PCE), light weight, and potential for cost reduction, their long-term stability and the pollution impact on the environment remain significant issues that need to be addressed urgently. The primary challenges in lead-based perovskites are caused by the segregation and migration of Pb²⁺ within the perovskite grain boundaries (GBs) and interface during device operation, which accelerate the degradation of perovskite and ultimately result in lead leakage. In this research, the stability of perovskite is improved through the in situ polymerization of DVB18C6, a polymerizable crown ether with selective lead chelating property within the perovskite GBs. The robust GBs formed by DVB18C6 optimize perovskite film defects and suppress device lead leakage. The champion device achieved a PCE of 26.78%, with a Pb²⁺ sequestration efficiency (SQE) of 95.14%. By integrating lead-chelating functionality with polymerizable groups, this approach improves the stability of PSCs and effectively mitigates lead leakage.

Piperidinium-functionalized ionomers are widely used alkaline-stable binders in anion exchange membrane water electrolyzers (AEMWEs). Although oxidative degradation has been demonstrated under strongly polarized, reactive oxygen species (ROS)-generating conditions, whether it can initiate through a distinct low-potential interfacial pathway before appreciable oxygen evolution remained unresolved. Here, we show that piperidinium groups undergo potential-induced interfacial oxidation on IrO₂ near 1.3 V vs the reversible hydrogen electrode under deoxygenated conditions, demonstrating that dissolved O₂ and diffusible O₂-derived oxidants are not required. Quantitative ¹³C nuclear magnetic resonance spectroscopy identifies formate as the dominant soluble product, accompanied by ion-exchange-capacity loss and damage to a backbone-integrated structural unit. Faradaic-efficiency measurements in a pure-water-fed AEMWE show a 16.9% H₂-normalized O₂ deficit at 1.6 V, consistent with a substantial non-oxygen evolution reaction (OER) contribution from piperidinium oxidation. These findings distinguish low-potential interfacial oxidation from diffusible-ROS-mediated degradation and establish anodic cation stability as critical to durable pure-water-fed AEMWEs and reliable OER catalyst evaluation.

Rechargeable Mg-metal batteries are attractive owing to their high volumetric capacity, safety, and resource abundance, yet their development is limited by severe polarization and sluggish cathode kinetics. Herein, a cation-vacancy engineering strategy is achieved through Mg substitution in NASICON-type NaTi₂(PO₄)₃. The optimized Mg_0.25Na_0.5Ti₂(PO₄)₃ cathode exhibits low voltage hysteresis (0.05 V), high rate capability (87% capacity retention at 500 mA g⁻¹), and long-term cycling stability (81% capacity retention after 500 cycles). A proof-of-concept pouch cell delivers a low polarization voltage of 0.067 V. Mechanistic investigations reveal a Mg−Na hybrid-ion storage mechanism, in which Na⁺ predominantly governs the reversible cathode reaction while Mg metal undergoes reversible stripping/plating at the anode. Vacancy engineering effectively regulates ion transport and structural reversibility, enabling highly stable electrochemical operation. This work demonstrates vacancy engineering as an effective strategy for developing high-performance NASICON cathodes for Mg-metal battery systems.

Electrolyte instability is an intrinsic issue that curtails the cycle life of lithium-ion batteries in energy storage devices. Residual trace moisture inevitably induces LiPF₆ hydrolysis, generating aggressive hydrofluoric acid (HF) during cycling, which degrades the cathode-electrolyte interphase (CEI) and accelerates solvent decomposition, thereby decreasing ionic conductivity and escalating interfacial impedance. Herein, we develop a multifunctional lithium trifluoro-N-methylacetamide (LiTFMA) salt to scavenge residual moisture and HF via a thermodynamic mechanism, thereby rejuvenating the ionic conductivity and lithium-ion transference number of degraded electrolytes. Furthermore, TFMA^– anions derive a thin and uniform nitrogen-containing CEI, which renovates degraded interphases and suppresses transition-metal dissolution. Consequently, retired NCM811 electrodes remanufactured with the LiTFMA-regenerated electrolyte deliver a capacity retention exceeding 80% after 300 cycles. This dual-functional strategy upcycles hazardous spent electrolytes into high-performance functional components, establishing a scalable pathway toward a circular battery economy.