Polyelectrolyte Brush Templated Multiple Loading of Pd Nanoparticles onto TiO2 Nanowires via Regenerative Counterion Exchange−Reduction

In this paper, a novel strategy was reported to produce ternary nanocomposite containing TiO 2 nanowires, poly[(dimethylamino)ethyl methacrylate] (PDMAEMA) brush and Pd nanoparticles. PDMAEMA brushes were grafted from catecholic initiator anchored on TiO 2 nanowires via surface-initiated atom transfer radical polymerization (SI-ATRP) at ambient conditions. The PDMAEMA uniformly covered the surface of TiO 2 nanowires and the two component of PDMAEMA and TiO 2 shows clear boundary interface. PDMAEMA brushes were derived with CH 3 I to form quaternized-PDMAEMA (Q-PDMAEMA) so as to facilitate anion exchange with PdCl 4 2−, which was followed by in situ reduction with NaBH 4 to obtain the TiO 2 nanowires-Q-PDMAEMA/Pd(0) ternary nanocomposite. Pd nanoparticles have very small size of about 2−4nm and monodisperse, uniformly distributed among polymer brush network. Interestingly, after reduction reaction, concurrent with generation of Pd nanoparticles, the ammonium cations were largely recovered, which allows further breath-in PdCl 4 2− counterions and uploads more Pd nanopaticles by repeated steps. The responsivity of both PDMAEMA and Q-PDMAEMA decorated TiO 2 nanowires was studied in response to pH and salt solution. The electrocatalytic behavior of the ternary nanocomposite was investigated.