Inorganic nanocatalysts play an important role in achieving future carbon neutrality by enhancing the efficiency of energy and material conversion. This chapter first focuses on the understanding of the nanoscale interface design of Cu electrode materials for high-efficiency electrochemical CO2 reduction (eCO2 R), which is currently one of the most studied reaction systems. Furthermore, the strategy for the construction of an eCO2 R system using CO2 captured by membrane-based direct air capture as the most promising CO2 capture and utilization system is presented.
Sensitive detection of biomarkers, such as proteins, is essential for early disease diagnosis and point-of-care testing systems. As a powerful tool in molecular detection, surface-enhanced Raman scattering (SERS) shows the advantages of high sensitivity and label-free characteristics. However, its application to protein detection has been constrained by the large size of them, which limits access to the narrow hotspot regions. To overcome this challenge, we developed gap-distance tunable Raman substrates by attaching gold nanoparticle self-assembled films onto hydrogels. These substrates allow dynamic adjustment of gap distances, facilitating better target molecule introduction with widened gaps and enhanced electromagnetic (EM) field strength with narrowed gaps. Triangular gold nanoplate (AuNT) arrays generate intense electromagnetic (EM) fields at the collective region formed by their closely spaced tips, which coincide with nanometer-scale vacant spaces capable of accommodating protein molecules. Further, we introduced a Gel Filter Trapping (GFT) method to actively deliver proteins into hotspots by exploiting the unique properties of hydrogels. In this system, protein solutions are absorbed into the hydrogel, while the three-dimensional polymer networks trap proteins at the gel surface, effectively directing them to hotspot areas. The combination of the AuTAG substrate and GFT method achieved ultrahigh sensitivity for protein detection down to the single-molecule level, with a wide quantification range spanning six orders of magnitude, demonstrating significant potential for practical SERS-based biomarker detection.
Aggregates of 13 atoms can form geometrically stable structures belonging to Ih , D5h , Oh , and D3h point groups. On the other hand, metal clusters with 18 valence electrons are known to be electronically stable, as predicted by the jellium model. Metal clusters with these dual stabilities are expected to be distinctive superatomic nanoclusters. In this article, we have successfully synthesized novel icosahedral cluster anions, M@Ag12 − (M = V, Nb, and Ta), in the gas phase and characterized by photoelectron imaging spectroscopy and DFT calculations. The photoelectron images of M@Ag12 − resemble one another, revealing that the clusters are valence iso-electronic systems. In addition, only a single ring is observed in the photoelectron images. This result manifests the perfect degeneracy of the five-fold 1D superatomic orbitals, thus providing solid evidence of the formation of icosahedral silver cages encapsulating the group V elements. DFT calculations also support that Ih structures are the most stable. The other highly symmetric structures (D5h , Oh , D3h ) are not obtained even in metastable states. The present study demonstrates that the concerted effect of the number of constituent atoms and valence electrons plays a significant role in tailoring physical and chemical properties of metal nanoclusters.