Nanoporous gyroid platinum with high catalytic activity from block copolymer templates via electroless plating

• DOI: 10.1038/am.2015.13
• Publication Date: 2015-04-03T05:55:52Z
• Authors: Chung-Fu Cheng; Han-Yu Hsueh; Chih-Huang Lai; Chun-Jern Pan; Bing-Joe Hwang; Chi-Chang Hu; Rong-Ming Ho
• Keywords: 01 natural sciences; 0104 chemical sciences

Nanoporous platinum (Pt) with a gyroid nanostructure was fabricated using a nanoporous polymer with gyroid nanochannels as a template. The nanoporous polymer template was obtained from the self-assembly of the degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by the hydrolysis of the PLLA blocks. Templated electroless plating can be conducted under ambient conditions to create a precisely controlled Pt gyroid nanostructure with high crystallinity in a PS matrix. After removal of the PS matrix, the well-interconnected nanoporous gyroid Pt can be successfully fabricated. Compared with commercially available catalysts, the nanoporous Pt possesses superior macroscopic stability and peak specific activity, benefiting from the well-defined network structure with robust texture and the growth of the low-index crystalline facets of Pt. Fabricating platinum catalysts into twisted, nanoporous ‘gyroid’ shapes dramatically boosts their stability and acivity, finds a new study. Carbon-supported platinum nanoparticles are potent catalysts for fuel cell devices, but they often fail prematurely due to corrosion effects and unwanted agglomeration. Rong-Ming Ho and co-workers from National Tsing Hua University in Taiwan investigated a way to improve the durability of such materials by electrochemically plating platinum onto block copolymers with gyroid frameworks — surfaces that symmetrically spiral around themselves into three-dimensional network morphology. After removing the polymer template, the researchers tested the nanoporous platinum gyroids and found they retained three times the activity of commerical catalysts after 3,000 reaction cycles. The team suspects that this enhanced catalytic performance is due to the gyroid's well-defined, periodic morphology and preferential growth of certain high-activity crystal facets. Nanoporous platinum (Pt) with a gyroid nanostructure was fabricated using a nanoporous polymer with gyroid nanochannels as a template. The nanoporous polymer template was obtained from the self-assembly of the degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by the hydrolysis of the PLLA blocks. Templated electroless plating can be conducted under ambient conditions to create a precisely controlled Pt gyroid nanostructure with high crystallinity in a PS matrix. After removal of the PS matrix, the well-interconnected nanoporous gyroid Pt can be successfully fabricated. Compared with commercially available catalysts, the nanoporous Pt possesses superior macroscopic stability and peak specific activity, benefiting from the well-defined network structure with robust texture and the growth of the low-index crystalline facets of Pt.