Ultrafast formation
of stable and self-assembled rhenium (Re)
nanoparticles (NPs) using a poly allylamine hydrochloride (PAH) scaffold
within 120 s of wet-chemical reaction at room temperature in aqueous
solution has been reported. The average diameters of the two different
sets of Re NPs synthesized are ∼0.7 ± 0.25 and ∼1.7
± 0.3 nm, which can be easily achieved by controlling the polymer
to Re7+ molar ratio. The small-size Re NPs are formed in
solution, self-assembled together to form the chain-like or necklace-like
structure. The synthesized Re NPs were used in two different potential
applications, such as in catalysis and in surface-enhanced Raman scattering
(SERS) studies. Catalysis study was done for 4-nitroaniline (4-NA)
reduction with excess NaBH4 taking two different sets of
Re NPs as catalyst. The highest catalytic rate for nitroaromatics
reduction ever reported of ∼1.52 × 10–1 min–1 has been observed with large-size Re NPs
as catalyst. In SERS, methylene blue (MB) was used as a Raman probe
molecule. Strong SERS enhancements were observed with both sets of
Re NPs due to their ultrasmall size, narrow interparticle gap, and
self-assembled structure in PAH scaffold. These closely tethered and
self-assembled Re NPs generated more surface active “hot
spots” that resulted in good SERS enhancement. The present
synthesis route is easy, cost effective, and fast and can generate
stable Re NPs which could further be applied in interdisciplinary
fields other than catalysis and SERS in the near future.