Transforming nanoscale and bulk metals into single atoms is crucial for the scalable production of single-atom catalysts (SACs), especially during pyrolysis. However, conventional equilibrium heating approaches often require prolonged operation to decompose metal aggregates, leading to tedious and time-consuming procedures for synthesizing SACs. In this study, we introduce high-temperature shock (HTS) strategy to enhance metal atomization, achieving the direct transformation of bulk copper (Cu) foil into single atoms in just 0.5 seconds at 1700 K. The HTS-produced Cu catalyst demonstrates a high content of 0.54 wt%, comparable to those achieved by commonly reported top-down strategies, indicating that the HTS method provides a compelling alternative for synthesizing Cu SACs from bulk Cu precursors. Structural analysis confirmed the synthesis of a Cu-N-C SAC with a Cu-N₄ coordination environment. This Cu-N₄ structure shows excellent catalytic performance for nitrite reduction to ammonia, achieving over 90% Faradaic efficiency across the entire working potential range and an ammonia production rate of up to 11.12 mg cm^-2 h^-1 at -1.2 V vs. RHE, surpassing other reported Cu-based electrocatalysts. Furthermore, ab initio molecular dynamics (AIMD) simulations reveal that transient high temperatures not only promote the formation of thermodynamically favorable Cu-N bonds but also prevent excessive sintering and aggregation of metal atoms.

Bound states in the continuum (BICs) supported by dielectric metasurfaces have significantly propelled the progress in optical technologies, notably for manipulating potent light-matter interactions. However, achieving a robust quasi-BIC mode with high Q factor by adjusting geometric parameters remains a challenge, primarily the Q factors strongly depend on the asymmetric parameters and the stringent fabrication requirements. Here, we propose a novel strategy to enhance the robustness of the Q factor through the continuous excitation of the magnetic dipole mode with low energy loss. Through a specialized multi-cell structure, the nanoarrays can continuously excite the magnetic dipoles contributed by different structural components over a broad range of geometrical parameters, exhibiting exceptional robustness and high quality resonance. This work provides a theoretical scheme that offers new directions for obtaining robust high Q resonances and developing potential applications for high-performance optical devices.

Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass, sustainability, environmental friendliness, and processability. Disodium terephthalate (Na₂C₈H₄O₄, Na₂TP), an organic salt with a theoretical capacity of 255 mAh·g⁻¹, is electroactive towards both lithium and sodium. However, its electrochemical energy storage (EES) process has not been directly observed via in situ characterization techniques and the underlying mechanisms are still under debate. Herein, in situ Raman spectroscopy was employed to track the de/lithiation and de/sodiation processes of Na₂TP. The appearance and then disappearance of the –COOLi Raman band at 1625 cm⁻¹ during the de/lithiation, and the increase and then decrease of the –COONa Raman band at 1615 cm⁻¹ during the de/sodiation processes of Na₂TP elucidate the one-step with the 2Li⁺ or 2Na⁺ transfer mechanism. We also found that the inferior cycling stability of Na₂TP as an anode for sodium-ion batteries (SIBs) than lithium-ion batteries (LIBs) could be due to the larger ion radium of Na⁺ than Li⁺, which results in larger steric resistance and polarization during EES. The Na₂TP, therefore, shows greater changes in spectra during de/sodiation than de/lithiation. We expect that our findings could provide a reference for the rational design of organic compounds for EES.

The composition and evolution of interfacial species play a key role during electrocatalytic process. Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed new light on the electrocatalytic reaction mechanism and develop highly efficient catalyst. However, directly probing the interfacial species is extremely difficult for most spectroscopic techniques due to complicated interfacial environment and ultra-low surface concentration. Herein, electrochemical core–shell nanoparticle enhanced Raman spectroscopy is utilized to probe the composition and evolution processes of interfacial species on Au@Pt, Au@Co, and Au@PtCo core–shell nanoparticle surfaces. The spectral evidences of interfacial intermediates including hydroxide radical (OH*), superoxide ion (O₂⁻), as well as metal oxide species are directly captured by in situ Raman spectroscopy, which are further confirmed by the both isotopic experiment and density functional theory calculation. These results provide a mechanistic guideline for the rational design of highly efficient electrocatalysts.

Monolayer graphene has attracted enormous attention owing to its unique electronic and optical properties. However, achieving an effective approach without applying electrical bias for manipulating the charge transfer based on graphene is elusive to date. Herein, we realized the manipulation of excitons’ transition from emitter to the graphene surface with plasmonic engineering nanostructures and firstly obtained large enhancements for photon emission on the graphene surface. The localized plasmons generated from the plasmonic nanostructures of shell-isolated nanoparticle coupling to ultra-flat Au substrate would dictate a consistent junction geometry while enhancing the optical field and dominating the electron transition pathways, which may cause obvious perturbations for molecular radiation behaviors. Additionally, the three-dimensional finite-difference time-domain and time-dependent density functional theory were also carried out to simulate the distributions of electromagnetic field and energy levels of hybrid nanostructure respectively and the results agreed well with the experimental data. Therefore, this work paves a novel approach for tunning graphene charge/energy transfer processes, which may hold great potential for applications in photonic devices based on graphene.

As state-of-the-art electrochemical energy conversion and storage (EECS) techniques, fuel cells and rechargeable batteries have achieved great success in the past decades. However, modern societies’ ever-growing demand in energy calls for EECS devices with high efficiency and enhanced performance, which mainly rely on the rational design of catalysts, electrode materials, and electrode/electrolyte interfaces in EESC, based on in-deep and comprehensive mechanistic understanding of the relevant electrochemical redox reactions. Such an understanding can be realized by monitoring the dynamic redox reaction processes under realistic operation conditions using in situ techniques, such as in situ Raman, Fourier transform infrared (FTIR), and X-ray diffraction (XRD) spectroscopy. These techniques can provide characteristic spectroscopic information of molecules and/or crystals, which are sensitive to structure/phase changes resulted from different electrochemical working conditions, hence allowing for intermediates identification and mechanisms understanding. This review described and summarized recent progress in the in situ studies of fuel cells and rechargeable batteries via Raman, FTIR, and XRD spectroscopy. The applications of these in situ techniques on typical electrocatalytic electrooxidation reaction and oxygen reduction reaction (ORR) in fuel cells, on representative high capacity and/or resource abundance cathodes and anodes, and on the solid electrolyte interface (SEI) in rechargeable batteries are discussed. We discuss how these techniques promote the development of novel EECS systems and highlight their critical importance in future EECS research.

Currently, lithium-ion batteries play a key role in energy storage; however, their applications are limited by their low energy density. Here, we design a facile method to prepare mesoporous ZnMn₂O₄ microspheres with ultrahigh rate performance and ultralong cycling properties by finely tuning the solution viscosity during synthesis. When the current density is raised to 2 A·g^-1, the discharge capacity is maintained at 879 mA·h·g^-1 after 500 cycles. The electrochemical properties of mesoporous ZnMn₂O₄ microspheres are better than that for most reported ZnMn₂O₄. To understand the electrochemical processes on the mesoporous ZnMn₂O₄ microspheres, in situ Raman spectroscopy is used to investigate the electrode surface. The results show that mesoporous ZnMn₂O₄ microspheres have a great potential as an alternative to commercial carbon anode materials.

Two-dimensional (2D) materials such as graphene and hexagonal boron nitride (h-BN) can be used as robust and flexible encapsulation overlayers, which effectively protect metal cores but allow reactions to occur between inner cores and outer shells. Here, we demonstrate this concept by showing that Pt@h-BN core–shell nanocatalysts present enhanced performances in H₂/O₂ fuel cells. Electrochemical (EC) tests combined with operando EC-Raman characterizations were performed to monitor the reaction process and its intermediates, which confirm that Pt-catalyzed electrocatalytic processes happen under few-layer h-BN covers. The confinement effect of the h-BN shells prevents Pt nanoparticles from aggregating and helps to alleviate the CO poisoning problem. Accordingly, embedding nanocatalysts within ultrathin 2D material shells can be regarded as an effective route to design high-performance electrocatalysts.