From spanning bulks to nanoclusters, surfaceenhanced Raman scattering (SERS) substrates of noble metals have frequently been explored for a long time. However, further downsizing nanoclusters to the atomic level, the surface plasmon resonance effect disappears, making the research on the SERS effect of atom-scale noble metal still lacking. Here, we discover a single-atom enhanced Raman scattering (SAERS) effect based on Au single atoms anchored on amorphous C 3 N 4 nanosheets (Au 1 / ACNs). The Au 1 /ACN exhibits an excellent spectral stability and reproducibility, as the uniform dispersed Au single atoms avoid the agglomeration of Au atoms to generate nonuniformly dispersed "hotspots" that suffer from poor SERS stability and reproducibility. Even only ∼2.5% Au-coated area in the laser illuminated area can yield an enhancement factor of 2.5 × 10 4 . The SAERS effect is attributed to the synergistic effect of Au single atoms anchored on amorphous C 3 N 4 , which increases the dipole moment and polarizability of molecules, enhancing the Raman signal of probe molecules. Furthermore, we propose a novel single-atom charge transfer mechanism that single-atom Au dominates higher electron delocalizability and higher electronic density of states near the HOMO level than the Au cluster. Our results will erect a new milepost for the application of single-atom materials in the field of enhanced Raman spectroscopy.

Amorphous materials are metastable solids with only short-range order at the atomic scale, which results from local intermolecular chemical bonding. The lack of long-range order typical of crystals endows amorphous nanomaterials with unconventional and intriguing structural features, such as isotropic atomic environments, abundant surface dangling bonds, highly unsaturated coordination, etc. Because of these features and the ensuing modulation in electronic properties, amorphous nanomaterials display potential for practical applications in different areas. Motivated by these elements, here we provide an overview of the unique structural features, the general synthetic methods, and the potential for applications covered by contemporary research in amorphous nanomaterials. Furthermore, we discussed the possible theoretical mechanism for amorphous nanomaterials, examining how the unique structural properties and electronic configurations contribute to their exceptional performance. In particular, the structural benefits of amorphous nanomaterials as well as their enhanced electrocatalytic, optical, and mechanical properties, thereby clarifying the structure−function relationships, are highlighted. Finally, a perspective on the preparation and utilization of amorphous nanomaterials to establish mature systems with a superior hierarchy for various applications is introduced, and an outlook for future challenges and opportunities at the frontiers of this rapidly advancing field is proposed.

No abstract

No abstract

A highly mineralized biomaterial is one kind of biomaterial that usually possesses a high content of crystal minerals and hierarchical microstructure, exhibiting excellent mechanical properties to support the living body. Recent studies have revealed the presence of inorganic amorphous constituents (IAC) either during the biomineralization process or in some mature bodies, which heavily affects the formation and performance of highly mineralized biomaterials. These results are surprising given the preceding intensive research into the microstructure design of these materials. Herein, we highlight the role of IAC in highly mineralized biomaterials. We focused on summarizing works demonstrating the presence or phase transformation of IAC and discussed in detail how IAC affects the formation and performance of highly mineralized biomaterials. Furthermore, we described some imitations of highly mineralized biomaterials that use IAC as the synthetic precursor or final strengthening phase. Finally, we briefly summarized the role of IAC in biomaterials and provided an outlook on the challenges and opportunities for future IAC and IAC-containing bioinspired materials researches.