Search

The high safety, compatible device size, superior energy density, and cost efficiency make in-plane aqueous zinc-ion microbatteries (AZIMBs) one of the most promising candidates for miniaturized energy storage. However, the inherent stacking structure within in-plane AZIMBs poses a hindrance to improving their energy density. Herein, this work presents a one-step approach for fabricating 3D cross-linked structures in V2CTx@rGO microelectrodes by laser processing technology, aiming to enhance the electrochemical performance of AZIMBs within a limited area by exploiting the vertical dimension of 3D architectures. The laser heat generated during laser processing induces the conversion of a 2D V2CTx@GO stacked structure into a 3D V2CTx@rGO skeleton structure, enabling the microelectrode to possess an optimal 3D conductive network, efficient charge transport pathway, and complete exposure of active sites. Moreover, the utilization of vanadium-based oxides derived from V2CTx MXene nanosheets on the surface during charging enhances the electrochemical performance of 3D AZIMBs. The obtained 3D VOx-V2CTx@rGO microelectrodes exhibit excellent rate performance, demonstrating an average reversible capacity ranging from 459 to 342 mA h g−1 at current densities varying from 0.8 to 2.5 A g−1, respectively. Additionally, the fabricated 3D VOx-V2CTx@rGO AZIMBs demonstrate exceptional flexibility and integrability, thus showing significant potential in microsized energy storage devices. [ABSTRACT FROM AUTHOR]

An efficient and durable free-standing electrocatalyst is the key to achieving pH-universal hydrogen evolution reaction under ultra-high current density. Herein, the free-standing three-stage concentric shaft structure of MoC@C shell-supported MoC nanoparticles anchored Ni@N-doped carbon nanotube vertical nanoarrays (P-MoC/Ni@NCNTs-MoC@C) are fabricated through a simple spraying and pyrolysis process. The formation of a MoC@C shell facilitates Ni nanoparticles' anchoring, resulting in Ni@N-doped carbon nanotube vertical arrays (Ni@NCNTs). Additionally, the Ni@NCNTs effectively capture the escaped molybdenum vapor, leading to the generation of MoC nanoparticles. The unique structure provides increased catalytic active sites and larger specific surface area, improving charge transfer and the release of bubbles. As such, the free-standing P-MoC/Ni@NCNTs-MoC@C catalyst exhibits lower overpotentials compared to previously reported articles, with values of 238.1 mV in 1.0 M KOH (1800 mA cm−2), 250.2 mV in 0.5 M H2SO4 (1800 mA cm−2), and 567.9 mV in 1.0 M PBS (1000 mA cm−2). Additionally, it represents low Tafel slopes of 71.1 mV dec−1, 67.4 mV dec−1, and 130.3 mV dec−1 in alkaline, acidic, and neutral condition, respectively. The current work may provide insight into the rational design of free-standing catalysts for practical applications. [ABSTRACT FROM AUTHOR]