Conventional non-precious-metal hydrogen evolution reaction catalysts suffer from excessive hydrogen adsorption and instability. To overcome this issue, we pioneered a high-entropy single-atom (HESA) catalyst by precisely anchoring multiple transition metals onto a carbon support. This HESA catalyst achieved record-breaking HER performance under alkaline conditions, with an overpotential of 44 mV@10 mA cm⁻² (comparable to commercial Pt/C catalysts) and stability exceeding 300 hours, resolving the long-standing activity-stability trade-off. Systematic characterization revealed that low-coordination metal sites induce significant metal-support charge redistribution. The electronegative support withdraws electrons from the metal centers, while π back-donation shifts the metal d-band center downward, optimizing the Gibbs free energy of the intermediate hydrogen atom (ΔG_H*). Atomic-scale imaging further confirmed uniform charge distribution and angstrom-level electric field response. Critically, adjacent multi-metal sites synergistically lower the energy barriers for water dissociation and hydrogen desorption through a cooperative electron-buffering effect. This work establishes entropy-driven microenvironment engineering as a paradigm for the synergistic optimization of active sites and electronic structures, paving the way for durable non-precious-metal catalysts.

In this work, we demonstrate the integration of a flat liquid jet sample delivery system into a compact soft X-ray absorption spectrometer using a tabletop laser-induced plasma light source. A high-speed flat liquid sheet is formed by the collision of two cylindrical jets. This micrometer-thick sheet is ideally suited for transmission-mode soft X-ray absorption spectroscopy utilizing krypton plasma emission. By applying the Lambert-Beer law, the thickness distribution of the jet was analyzed in detail. Measurements on water, focusing on the oxygen K-edge, revealed a sheet thickness distribution ranging from 500 nm to 1 micrometer over a length of 3.8 mm. Furthermore, we investigated aqueous solutions of iron salts, capturing near-edge X-ray absorption fine structure spectra over a broad spectral range from the nitrogen K-edge to the iron L-edge. Focused analysis of iron species in aqueous solution enabled us to quantitatively distinguish the oxidation states of Fe2+ and Fe3+ at the iron L-edge. Our results were compared with measurements obtained under similar conditions at a synchrotron.

Although two-dimensional (2D) conductive metal-organic frameworks (cMOFs) are attractive for energy applications due to their intrinsic electrical conductivity and redox activity, alleviating the restricted mass transport within long-range microporous channels remains a significant challenge. Herein, we propose a tandem assembly and etching chemistry approach to introduce vertically aligned mesopores into the micropores of cMOFs via a bifunctional modulator. Synchrotron radiation spectroscopy and morphological analysis revealed that the finely tuned ammonia modulator first coordinates with Zn2+ during the initial self-assembly of cMOF oligomers to form defects, subsequently triggering the formation of mesoporous cMOFs through in-situ etching. In-situ spectroscopy and theoretical simulations further revealed that this unique vertically aligned mesoporous structure shortens the microporous channels by two orders of magnitude and alleviates the inherent ion accumulation within the micropores, resulting in a fivefold increase in Na+ transport speed, remarkable rate performance at 250 C, and sodium storage lifetime exceeding 50,000 cycles. Our approach opens new avenues for introducing mesopores into microporous cMOFs, applicable to advanced energy applications and beyond.