Insight into the Evolution of Ordered Mesoporous sp2 Carbonaceous Material Derived from Self-Assembly of a Block Copolymer.

Block-copolymer-derived ordered mesoporous carbon (OMC) materials have great potential in many applications, such as adsorption, catalysis, and energy conversions; however, their formation process and the kinetic mechanism remain unclear. Herein, a N-doped OMC (N-OMC) with sp2-bonded C atoms is developed via self-assembly of the polystyrene-block-poly(4-vinyl pyridine) block copolymer. By correlating the external morphologies with the internal chemical states, the formation process can be concluded as follows: (1) pore evolution via polystyrene domain degradation and (2) regularization and graphitization of the residual carbon via the removal of sp3 C atoms. In addition, the thickness of the N-OMC shows a power function relationship with the spin-coating rate, and the N content can be incredibly increased up to 26.34 at. % in an NH3 carbonization atmosphere. With the as-prepared N-OMC as the support for loading of the pseudo-atomic-scale Pt (Pt/N-OMC), a high electrochemical active surface area value of 99.64 m2·g-1 and a half-wave potential (E1/2) of 0.850 VRHE are achieved, showing great potential in developing single-atom electrocatalysts.

Synthesis of Ordered Pt Nanocube Arrays Directed by Block Copolymer Nanotemplate and Their Potential on Ethanol Oxidation Reaction.

In this work, well-ordered platinum (Pt) nanocubes (NCs), with precise control on the size and the spatial arrangement, are synthesized from a microemulsion overgrowth in a block copolymer (BC) nanotemplate. The nanovials on this self-assembled BC template serve as microreactors for the reduction of the HCl/H2PtCl6 precursor and direct the ordered periodic arrangement of the reduced Pt nanoparticles (NPs). As the content of HCl increases from 0% to 25%, the Pt NPs evolve from quasi-spheres to NCs, for which the density functional theory (DFT) computation reveals that the different adsorption energies of Cl and HCl dominate this morphology transition. For their potential application in fuel cells, the electrochemical catalysis of the Pt NCs demonstrates a 2.8-fold mass activity in contrast to the commercial JM 40% catalyst at the same Pt loading in ethanol oxidation reaction (EOR) and a good stability of 2.2% ECSA loss over 10 000 CV cycling.