The novel PDDA-NPCNs/Ti3C2 hybrids via an electrostatic attraction self-assembly approach effectively accelerate reaction kinetics and improve electrochemical performance as PIBs anodes.

Despite remarkable progress in hybrid perovskite solar cells (PSCs), the concern of toxic lead ions remains a major hurdle in the path towards PSC's commercialization; tin (Sn)‐based PSCs outperform the reported Pb‐free perovskites in terms of photovoltaic performance. However, it is of a particularly great challenge to develop effective passivation strategies to suppress Sn(II) induced defect densities and oxidation for attaining high‐performance all‐inorganic CsSnI3 PSCs. Herein, a facile yet effective thioamides passivation strategy to modulate defect state density at surfaces and grain boundaries in CsSnI3 perovskites is reported. The thiosemicarbazide (TSC) with SCN functional groups can make strong coordination interaction with charge defects, leading to enhanced electron cloud density around defects and increased vacancy formation energies. Importantly, the surface passivation can reduce the deep level trap state defect density originated from undercoordinated Sn2+ ion and Sn2+ oxidation, significantly restraining nonradiative recombination and elongating the carrier lifetime of TSC treated CsSnI3 PSCs. The surface passivated all‐inorganic CsSnI3 PSCs based on an inverted configuration delivers a champion power conversion efficiency (PCE) of 8.20%, with a prolonged lifetime over 90% of initial PCE, after 500 h of continuous illumination. The present strategy sheds light on surface defect passivation for achieving highly efficient all‐inorganic lead‐free Sn‐based PSCs.

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Taking into consideration the advantages of the highly theoretical capacity of antimony (Sb) and abundant surface redox reaction sites of Na+ pre-intercalated 3D porous Ti3C2T x (Na–Ti3C2T x ) architectures, we elaborately designed the Sb/Na–Ti3C2T x hybrid with Sb nanoparticles homogeneously distributed in 3D porous Na–Ti3C2T x architectures through a facile electrostatic attraction and carbothermic reduction process. Na–Ti3C2T x architectures with more open structures and larger active specific surface area not only could certainly alleviate volume changes and hinder the aggregation of Sb nanoparticles in the cycling process to improve the structural stability but also significantly strengthen the electron-transfer kinetics and provide unblocked K+ diffusion channels to promote ionic/electronic transport rate. Furthermore, the ultrafine Sb nanoparticles could efficiently shorten K+ transport distance and expose more accessible active sites to improve capacity utilization. DFT calculations further indicate that the Sb/Na–Ti3C2T x anode effectively decreases the adsorption energy of K+ and accelerates the potassiation process. Benefiting from the synergistic effect, it exhibits an outstanding specific capacity of 392.2 mAh g–1 at 0.1 A g–1 after 450 cycles and a stable capacity reservation with a capacity fading rate of 0.03% per cycle at 0.5 A g–1. Our work may encourage further research on advanced MXene-based hybrid materials for high-performance PIBs.

Rechargeable Li-O 2 batteries are promising due to their superior high energy density but subject to sluggish oxygen reduction/evolution kinetics. Developing highly efficient catalysts to improve catalytic activity and alleviate oxidation-reduction overpotential of Li-O 2 batteries is of great challenge and importance. Herein, a CO 2 -assisted thermal-reaction strategy is developed to fabricate isolated semi-metallic selenium single-atom-doped Ti 3 C 2 MXene catalyst (SASe-Ti 3 C 2 ) as cathodes for high-performance Li-O 2 batteries. The isolated moieties of single Se atom catalysis centers can function as active catalytic centers to drastically enhance the intrinsic LiO 2 -absorption ability and thus fundamentally modulate the formation/decomposition mechanism of lithium peroxide (Li 2 O 2 ) discharge product, thus demonstrating greatly enhanced redox kinetics and efficiently ameliorated overpotentials. Theoretical simulations reveal that the interaction between Se-involved moieties and Ti 3 C 2 substrate greatly enhances the intrinsic LiO 2 -absorption ability and fundamentally promotes the charge transfer between electrode and Li 2 O 2 product, deeply ameliorating the round-trip overpotential. The well-designed SASe-Ti 3 C 2 electrode exhibits decreased charge/discharge polarization (1.10 V vs Li/Li + ), ultrahigh discharge capacity (17 260 mAh g −1 at 100 mA g −1 ), and superior durability (170 cycles at 200 mA g −1 ) as cathode for Li-O 2 batteries. The promising results will shed light on the design of highly efficient catalysts for oxygen-involved systems of future investigation.

Despite high theoretical capacity and earth-abundant resources, the potential industrialization of potassium–sulfur (K–S) batteries is severely plagued by poor electrochemical reaction kinetics and a parasitic shuttle effect. Herein, a facile low-temperature pyrolysis strategy is developed to synthesize N-doped Co nanocluster inlaid porous N-doped carbon derived from ZIF-67 as catalytic cathodes for K–S batteries. To maximize the utilization efficiency, the size of Co nanoparticles can be tuned from 7 nm to homogeneously distributed 3 nm clusters to create more active sites to regulate affinity for S/polysulfides, improving the conversion reaction kinetics between captured polysulfides and K2S3/S, fundamentally suppressing the shuttle effect. Cyclic voltammetry curves, Tafel plots, electrochemical impedance spectroscopy, and density functional theory calculations ascertain that 3 nm Co clusters in S–N–Cos–C cathodes exhibit superior catalytic activity to ensure low charge transfer resistance and energy barriers, enhanced exchange current density, and improved conversion reaction rate. The constructed S–N–Cos–C cathode delivers a superior reversible capacity of 453 mAh g–1 at 50 mA g–1 after 50 cycles, a dramatic rate capacity of 415 mAh g–1 at 400 mA g–1, and a long cycling stability. This work provides an avenue to make full use of high catalytic Co nanoclusters derived from metal–organic frameworks.

TiNb 2 O 7 (TNO) is a competitive candidate of a fastcharging anode due to its high specific capacity. However, the insulator nature seriously hinders its rate performance. Herein, the La 3+ -doped mesoporous TiNb 2 O 7 materials (La−M−TNO) were first synthesized via a facile one-step solvothermal method with the assistance of polyvinyl pyrrolidone (PVP). The synergic effect of La 3+ doping and the mesoporous structure enables a dual improvement on the electronic conductivity and ionic diffusion coefficient, which delivers an impressive specific capacity of 213 mAh g −1 at 30 C. The capacity retention (@30C/@1C) increases from 33 to 53 and 74% for TNO, M−TNO, and La−M−TNO (0.03), respectively, demonstrating a step-by-step improvement of rate performance by making porous structures and intrinsic conductivity enhancement. DFT calculations verify that the enhancement in electronic conductivity due to La 3+ doping and oxygen vacancy, which induce localized energy levels via slight hybridization of O 2p, Ti 3d, and Nb 4d orbits. Meanwhile, the GITT result indicates that PVP-induced self-assembly of TNO accelerates the lithium ion diffusion rate by shortening the Li + diffusion path. This work verifies the effectiveness of the porous structure and highlights the significance of electronic conductivity to rate performance, especially at >30C. It provides a general approach to low-conductivity electrode materials for fast Li-ion storage.

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