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The design of pseudocapacitive electrodes that exhibit high‐rate and high volumetric capacitances is a big challenge, since it requires subtle modulation of ion‐intercalation structures that are able to achieve high electrochemical activity, fast ion transport, and facilitated electron transfer, simultaneously. Herein, controllable and selective etching of B atoms from B‐doped Ti3AlC2 precursors is reported, which generates boron‐vacancy doped MXene (B‐V‐MXene) nanosheets with finely‐regulated, ion‐intercalation structures. Electrochemical studies and density‐functional‐theory calculations demonstrate that Ti around vacancies possess higher surface‐redox activity with protons than those on pristine MXenes for the improvement of capacitances. In addition, interlayer spacing can be optimized on B‐V‐MXenes in promoting proton intercalation. More importantly, the dopant B atoms can increase the electron density on Ti, facilitating the adsorption of the intercalated protons; and further, B 2p‐Ti 3d hybridized band sits closer to the Fermi energy than that of C 2p bands, which bridges the energy gap for electron transfer in the pseudo‐capacitive reaction. With synergy of all these effects, the novel B‐V‐MXene compact electrodes can deliver the previously unmatched high volumetric capacitances of 807 F cm−3 at 1,000 mV s−1 and 1,815 F cm−3 at 5 mV s−1, with excellent cycle stability over 10,000 cycles. [ABSTRACT FROM AUTHOR]

The two‐step sequentially deposition strategy has been widely used to produce high‐performance FAPbI3‐based solar cells. However, due to the rapid reaction between PbI2 and FAI, a dense perovskite film forms on top of the PbI2 layer immediately and blocks the FAI diffusion into the bottom of the PbI2 film for a complete reaction, which results in a low‐efficiency and limited reproducibility of perovskite solar cells (PSCs). Here, high‐quality α‐FAPbI3 perovskite films by crystal growth regulation with 4‐fluorobenzamide additives is fabricated. The additives can interact with FAI to suppress the fast reaction between the FAI and PbI2 and effectively passivate the under‐coordinated Pb2+ or I‐ defects. As a result, α‐FAPbI3 perovskite films with low trap density and large grain size are prepared. The modified PSCs present a high‐power conversion efficiency of 24.08%, maintaining 90% of their initial efficiency after 1400 h in high humidity. This study provides an efficient strategy of synergistic crystallization and passivation to form high‐quality α‐FAPbI3 films for high‐performance PSCs. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, by using the superabsorbent polymers (SAPs) from baby diaper, the 3D porous composites decorated with NiO and Ni nanoparticles (NNSCs) have been prepared via a facile dissolving‐freeze drying and subsequent annealing reactions. The porous carbon matrix (PCM) derived from the SAPs also provides a continuous highly conductive network to facilitate the fast charge transfer and form a stable solid electrolyte interface film. Furthermore, NNSC can exhibit the high specific capacity and excellent cycle performance as anode materials for lithium‐ion batteries. And more importantly, employing the PCM derived from baby diaper offers a green approach for other energy storage materials. [ABSTRACT FROM AUTHOR]

Sluggish ion diffusion of large sodium ions is one of the main drawbacks challenging the development of metal selenides‐based anode materials for sodium‐ion batteries (SIBs). A spin‐state regulating strategy is first proposed in this work to lift the p‐band center (ɛp) of Se for a fast Na+ transfer kinetic in (Co,Cu)Se2. By utilizing the electron transfer from Cu to Co, the π‐symmetry t2g of Co is fully occupied to decrease the spin polarization. The resultant electron repulsion between Co and Se weakens Co–Se bond to lift the ɛp of Se. The enhanced sodium adsorption energy effectively accelerates the ion transfer at the active material–electrolyte interface. As a result, the (Co,Cu)Se2/NC electrode exhibits an superior sodium storage performance with a capacity of 445 mAh g−1 at 0.2 A g−1, 312 mAh g−1 at 50 A g−1, and 363 mAh g−1 after 10 000 cycles at 10.0 A g−1. The insight into the working mechanism of regulating spin‐state of metals to lift the p‐band center of Se can provide guidelines for the development of both metal selenides‐based anode material and high‐performance SIBs. [ABSTRACT FROM AUTHOR]

Developing active, robust, and nonprecious electrocatalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is highly crucial and challenging. In this work, a facile strategy is developed for scalable fabrication of dicobalt phosphide (Co2P)–cobalt nitride (CoN) core–shell nanoparticles with double active sites encapsulated in nitrogen‐doped carbon nanotubes (Co2P/CoN‐in‐NCNTs) by straight forward pyrolysis method. Both density functional theory calculation and experimental results reveal that pyrrole nitrogen coupled with Co2P is the most active one for HER, while Co–N–C active sites existing on the interfaces between CoN and N‐doped carbon shells are responsible for the ORR and OER activity in this catalyst. Furthermore, liquid‐state and all‐solid‐state Zn–air batteries are equipped. Co2P/CoN‐in‐NCNTs show high power density as high as 194.6 mW cm−2, high gravimetric energy density of 844.5 W h kg−1, very low charge–discharge polarization, and excellent reversibility of 96 h at 5 mA cm−2 in liquid system. Moreover, the Co2P/CoN‐in‐NCNTs profiles confirm excellent activity for water splitting. Dicobalt phosphide–cobalt nitride core–shell particles act as double active centers and are encapsulated into the channel of N‐doped carbon nanotubes by an in situ one‐step self‐assembly and confined pyrolysis approach, which is demonstrated to afford trifunctional performance in catalyzing hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction for Zn–air batteries and water splitting. [ABSTRACT FROM AUTHOR]