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.

Rechargeable Li–S batteries (LSBs) are emerging as an important alternative to lithium-ion batteries (LIBs), owing to their high energy densities and low cost; yet sluggish redox kinetics of LiPSs results in inferior cycle life. Herein, we prepared multifunctional self-supporting hyphae carbon nanobelt (HCNB) as hosts by carbonization of hyphae balls of Rhizopus, which could increase the S loading of the cathode without sacrificing reaction kinetics. Trace platinum (Pt) nanoparticles were introduced into HCNBs (PtHCNBs) by ion-beam sputtering deposition. Based on the X-ray photoelectron spectroscopy analyses, the introduced trace Pt regulated the local electronic states of heteroatoms in HCNBs. Electrochemical kinetics investigation combined with operando Raman measurements revealed the accelerated reaction mechanics of sulfur species. Benefiting from the synergistic catalytic effect and the unique structures, the as-prepared PtHCNB/MWNCT/S cathodes delivered a stable capacity retention of 77% for 400 cycles at 0.5 C with a sulfur loading of 4.6 mg cm⁻². More importantly, remarkable cycling performance was achieved with an high areal S loading of 7.6 mg cm⁻². This finding offers a new strategy to prolong the cycle life of LSBs.

Among the alternatives to lithium-ion batteries, lithium–sulfur (Li–S) batteries are considered as an attractive option because of their high theoretical energy density of 2570 Wh kg⁻¹. However, the application of the Li–S battery has been plagued by the rapid failure of the Li anode due to the Li dendrite growth and severe parasitic reactions between Li and lithium polysulfides. The physicochemical properties of the solid–electrolyte interphase have a profound impact on the performance of the Li anode. Herein, a lithium polyacrylic acid/lithium nitrate (LPL)-protective layer is developed to inhibit the dendrite Li growth and parasitic reactions by tailoring the spatial distribution and content of LiN_xO_y and Li₃N at the SEI. The modified SEI is thoroughly investigated for compositions, ion transport properties, and Li plating/stripping kinetics. Consequently, the Li–S cell with a high S loading cathode (5.0 mg cm⁻²), LPL layer-protected thin Li anode (50 μm), and 40 μL electrolyte shows a long life span of 120 cycles. This work evokes the avenue for regulating the spatial distribution of inorganic nitride at the SEI to suppress the formation of Li dendrites and parasitic reactions in Li–S batteries and perhaps guiding the design of analogous battery systems.