Despite extensive theoretical studies on d-band engineering, the lack of direct experimental evidence at the orbital level continues to hinder the rational design of efficient electrocatalysts for the alkaline hydrogen evolution reaction (HER), particularly in anion-exchange membrane water electrolyzers (AEMWEs). Herein, we report a RuCoN alloy anchored on nitrogen-doped carbon nanotubes (RuCoN-NCNT) that achieves outstanding HER performance, delivering an ultralow overpotential of 13 mV at 10 mA·cm⁻² and long-term durability exceeding 60 h at 100 mA·cm⁻². To unravel the intrinsic electronic structure–activity relationships, we employ advanced spectroscopic techniques, including in-situ Raman and rarely utilized inverse photoemission/ultraviolet photoelectron spectroscopy (IPES/UPS). The orbital-resolved measurements reveal that pyridinic-N mainly converts to RuCoN, which reinforces the structural robustness by enhancing electronic coupling, and pyrrolic-N and metal-N pull the d-band center upward and broaden the conduction band, optimizing H*/H₂O adsorption and conversion. These together enable optimized electron distribution for high catalytic activity. The synergy between nitrogen configurations and the RuCoN alloy creates electronically integrated catalytic sites with optimized charge distribution. When assembled in a full AEMWE device, the optimal RuCoN-NCNT-400 catalyst surpasses commercial Pt/C, demonstrating industrial-level activity and long-term stability. This work provides direct experimental validation of d-band modulation, establishing a framework for orbital-level catalyst engineering and bridging the gap between theoretical predictions and practical HER electrocatalysis.

Lithium–sulfur batteries (LSBs) offer high energy density and eco-friendly sulfur cathodes, but commercialization is hindered by slow sulfur redox kinetics and the “shuttle effect”, which limit capacity and cycle life. This study used inverse photoemission spectroscopy and ultraviolet photoelectron spectroscopy (IPES/UPS) to investigate the S redox mechanism. The BNOC matrix, with fully occupied electron states near the Fermi level, enhances conductivity and oxygen covalency by downshifting the lowest unoccupied molecular orbital (LUMO) to hybridize with the highest occupied molecular orbital (HOMO). This matrix traps lithium polysulfides (LiPSs), where loosely bound oxygen atoms facilitate S redox, particularly the key Li₂S ↔ LiPSs conversion. Additionally, the strong covalent B–N bonds, synergizing with the hollow BNOC cages, confine S redox reactions within structurally stable nanoscale spaces, effectively mitigating the shuttle effect. As a result, the LSB in our study delivers extended 1300 cycles at 4 C, maintaining 337.8 mAh·g⁻¹ specific capacity. It also possesses a high areal capacity of 7.76 mAh·cm⁻² at a high sulfur loading of 5.6 mg·cm⁻², and is capable of powering a pouch-type LSB at a current density of 8 mAh·cm⁻² for over 15 cycles. This study lays a foundation for the rational design and performance enhancement of future LSB.

Solar irradiation can efficiently promote the kinetics of the oxygen evolution reaction (OER) during water splitting, where heterojunction catalysts exhibit excellent photoresponsive properties. However, insights into the origins of photoassisted OER catalysis remain unclear, especially the interfaced promotion under convergent solar irradiation (CSI). Herein, novel allotropic Co_5.47N/CoN heterojunctions were synthesized, and corresponding OER mechanisms under CSI were comprehensively uncovered from physical and chemical aspects using the in situ Raman technique and electrochemical cyclic voltammetry method. Our results provide a unique mechanism where high-energy UV light promotes the Co^3+/4+ conversion process in addition to the ordinary photoelectric effect excitation of the Co²⁺ material. Importantly, visible light under CSI can produce a photothermal effect for Co²⁺ excitation and Co^3+/4+ conversion, which promotes the OER significantly more than the usual photoelectric effect. As a result, Co_5.47N/CoN (containing 28% CoN) obtained 317.9% OER enhancement, which provides a pathway for constructing excellent OER catalysts.