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Dimensional engineering is promising for achieving a high power conversion efficiency (PCE) and long‐term stability of perovskite solar cells (PSCs). However, insulated organic spacers in 2D perovskites often severely hinder carrier transport between the internal layers of devices. Herein, the "protonation‐induced localized transformation of 2D perovskites" is proposed to overcome the low carrier transport and conductivity of 2D/3D perovskite heterojunctions. Metformin, with its multiple amine groups and a substantial difference between its pKa value and perovskites, is protonated in an acidic environment or directly converted into the hydrochloride salt for the surface passivation of methylammonium lead iodide. This leads to the transformation of disorderedly oriented layered 2D perovskite into vertically oriented ones at grain boundaries. Consequently, the PCE of a carbon‐based PSC treated by protonated metformin increased considerably, reaching an optimal level of 14.13%. Additionally, applying this passivation strategy to a planar device (ITO/4PADCP/perovskite/PCBM/BCP/Ag) increased PCE from 20.82% to 22.09%, confirming the applicability of the strategy. To demonstrate the practical stability, an integrated PSC–supercapacitor device is assembled, which shows good cycling stability. This article introduces a novel method to improve carrier transport in 2D/3D perovskite heterojunctions, promoting the extensive utilization of dimensional engineering. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks bearing coordinatively unsaturated metal sites (CUSs) exhibit distinctive interactions toward guest molecules, thereby presenting intriguing properties in photocatalytic applications. Herein, an adaptable strategy is established to create 2D metal‐porphyrin frameworks while engineering the CUSs based on the use of bivalent metal nodes (Zn2+, Co2+, Cu2+, Ni2+, Cd2+) and Zr‐O clusters. The strong surface‐coordination effect reduces the energy barriers to activate acrylate monomers adsorbed to the nanosheet frameworks, enabling the generation of anion radicals through a broadband light‐induced electron transfer pathway. Particularly, the photocatalytic cycle offers a hole‐mediated deactivation mechanism to regulate the radical concentrations in the polymerization system, while the propagating chains exhibit a surface‐confined growth behavior that significantly inhibits recombination terminations. Extensive mechanistic studies and theoretical calculations reveal the molecular‐level guest‐framework interactions and establish the guidelines to screen metal centers for fabricating valid photocatalysts and monomers compatible with photo‐regulated polymerization. A series of ultrahigh molecular weight polymers with Mn > 1 000 000 and relatively low dispersity (Đ ≈ 1.5) are obtained upon exposure to the full spectrum of visible light. This study provides novel inspirations for harnessing natural sunlight to drive macromolecular synthesis with minimal energy consumption. [ABSTRACT FROM AUTHOR]

The increasing amount of electronic exerts a profound impact on both the environment and human health. Looking forward, it is imperative to develop electronic products that can degrade under mind condition, which largely relies on the development of degradable organic semiconductors (OSCs). Yet, designing degradable OSCs with decent electrical properties is challenging. In this study, two degradable n‐type OSCs based on a dynamic covalent C═C bond formed via the Knoevenagel condensation reaction are reported. The cleavage of Knoevenagel formed C═C bond through a retro‐Knoevenagel process imparts the degradability of these two OSCs in the weak base, particularly in the human‐friendly α‐amino acid of lysine. Meanwhile, the C═C bond formed by Knoevenagel reaction preserves optimal backbone planarity and good electron delocalization of the molecules. This, in turn, endows the OSCs with commendable electron transport performance, achieving an electron mobility of up to 0.57 cm2 V⁻¹ s⁻¹ in organic thin‐film transistors. This work provides a new insight into the molecular design strategy for the development of OSCs with degradability and good electrical properties. [ABSTRACT FROM AUTHOR]

In the quest to elevate the sodium‐ion intercalation kinetics of transition metal oxide electrodes, the intrinsic low conductivity of these materials often acts as a bottleneck, restricting Na+ storage. Herein, the mechanism behind sodium‐ion diffusion kinetics in MnO2 is explored, specifically focusing on the manipulation of π* antibonding orbital occupancy. This is accomplished through strategic doping with strongly electron‐withdrawing Rh3+ (t2g6eg0), enhancing the hybridization of Mn 3d‐O 2p orbitals and significantly increasing the electrical conductivity of MnO2. Density functional theory (DFT) calculations and X‐ray absorption spectroscopy (XAS) results demonstrate that the smaller orbital energy difference between Rh3+eg and Mn4+t2g, compared to that between Rh3+eg and Mn4+eg, fosters direct electron transfer from the Mn4+t2g to the vacant Rh3+eg. This electron movement induces an upshift in the Mn‐t2g orbital energy levels while concurrently diminishing the occupancy of π* antibonding orbitals formed via Mn t2g‐O 2p hybridization. The resultant Rh‐MnO2 electrode exhibits an impressive specific capacity of 335 F g−1 at 1 A g−1 and a substantial rate capacity of 224.8 F g−1 at 20 A g−1. This investigation elucidates the intricate mechanism underlying the sluggish kinetics of sodium ion intercalation within transition metal oxide frameworks. [ABSTRACT FROM AUTHOR]

Electrophysiological signals are commonly used to assess health performance, providing valuable information on body status. However, stable signal acquisition by commercial Ag/AgCl gel or metal electrodes is susceptible to electrode/skin interface interferences due to perspiration and motion during exercise. To address this challenge, herein a sweat absorbing skin electrode (SAE) is designed, which can not only become softer and more adhesive but also enhance conductivity after sweat during exercise. The resulting stable interface between SAE/skin after sweat enables accurate and continuous electrophysiological measurement during exercise. SAE is demonstrated by assembly of MXene (Ti3C2TX) aerogel and zwitterionic polymer, where Ti3C2TX aerogel works as conductive skeleton and zwitterionic polymer endows skin conformability as well as expediting interfacial charge transfer by the inherent ions. SAE can monitor a variety of electrophysiological signals during exercise. As an example, electromyogram (EMG) signals are acquired to assess muscle fatigue, which is impossible by commercial gel electrodes. Via machine learning, the correlation between EMG and physiological markers (body fat percentage (BF) and body mass index (BMI)) are constructed. The research shows that sweat‐absorbing SAEs can reliably monitor electrophysiological signals during exercise, such as muscle status, leading to evidence‐based scientific guidelines for sports and rehabilitation training. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction reaction (NO3RR) offers a route to balanced nitrogen cycle and sustainable ammonia production. However, unsatisfied performance in neutral media arising from competitive hydrogen evolution reaction and inefficient hydrogenation impede the further applications of NO3RR. Herein, the rational design of RuNi alloy nanostructures is reported. Benefited from the synergism effect between Ru and Ni, Ru20Ni80 alloy exhibits a high NH3 Faradaic efficiency of 98.02% at −0.35 V (vs reversible hydrogen electrode (RHE)) and a large NH3 yield rate of 27.88 mg mgcat−1 h−1 at −0.65 V (vs RHE). Importantly, the atomic scale cooperation between Ru and Ni active sites endows RuNi alloy a close‐to‐unity NH3 selectivity via HNO* pathway. Theoretical calculations have revealed that the interactions between Ru and Ni optimize the electronic structures of Ru20Ni80 alloy, where Ru sites with enhanced electroactivity improve the generation of active hydrogens and more electron‐rich Ni sites facilitate the reduction of nitrate. Accordingly, the adsorption strengths of key intermediates become stronger and the energy barriers of NO3RR are reduced to guarantee efficient NO3RR. Furthermore, a flow‐type reactor coupled with coprecipitation is established to achieve continuous NH3 generation and recovery as struvite. [ABSTRACT FROM AUTHOR]