Au-Al intermetallic compounds: A series of more efficient LSPR materials for hot carriers-based applications than noble metal Au

Hot carriers generated by the non-radiative decay of localized surface plasmon resonance (LSPR) of noble metal nanoparticles are widely investigated in applications ranging from solar energy conversion to photocatalysis, and photodetection. From the perspective of sustainable development of the LSPR based applications, it is important to find metallic materials that are cheap and plentiful and show excellent hot carrier properties. In this context, we investigate the possibility of alloying Au with Al to develop efficient LSPR materials for hot carriers-based applications. Taking thermodynamically stable AuAl2 and AuAl as examples, we study their electronic structures, generation rates, energetic distribution, relaxation times, and mean free paths of hot carriers originating from direct and phonon-assisted indirect electronic transitions, which are two of the main channels for generating high-energy hot carriers from the decay of LSPR, and compare the results with that of Au and Al metals. It is found that both AuAl2 and AuAl show larger hot carrier generation rates than Au and the resulting hot carriers are energetically higher than that in Au. Meanwhile, the transport properties of hot carriers in AuAl2 and AuAl outperform that of Au, which is manifested through comparable or even longer relaxation times and mean free paths. Consequently, it is believed that the Au-Al intermetallic compounds should be a series of efficient LSPR materials for hot carriers-based applications, which is comparable with or even better than the noble metal Au. These results are helpful for the sustainable development of related fields.