Drastic performance enhancement of photoluminescence and water electrolysis by local-magnetic-field-assisted LSPR of Ag NPs and NCs

A novel method is presented for drastically improving the local surface plasma resonance (LSPR) effect of noble metal nanoparticles (NPs) and nanoclusters (NCs). This is realized by magnetizing particles comprising a ferrimagnetic core and a noble metal nanoshell. In this study, we prepared Fe3O4 @SiO2 @Ag composite particles. Ag NPs and NCs had the size of 10–15 nm and 2–3 nm, respectively. The photoluminescence (PL) intensities of ZnO and YAG:Ce substrates coated with the magnetic composite particles increased by 160 % and 50 %, respectively, after magnetization under a magnetic field of 18 mT compared to the unmagnetized state. The activity of Ni-foam-based-Fe3O4 @SiO2 @Ag working electrode for water electrolysis was also significantly improved after magnetization. The increasing rate of current density after magnetization was 226 mA∙cm−2/0.1 V, which is higher than 158 mA∙cm−2/0.1 V before the magnetization. The mechanism for drastic performance enhancement of PL and water electrolysis postulates that after magnetization, the remanence of the ferrimagnetic Fe3O4 core provides a local magnetic field to strengthen the local electric field in the confined area of Ag NPs/NCs. It was confirmed by the higher intensity of peaks in Raman spectroscopy and contributed to the enhancement of LSPR effect. This efficient and practical approach to magnetization-induced LSPR improvement has potential application prospects in LSPR-related fields.