Polypyrrole nanostructures modified with mono- and bimetallic nanoparticles for photocatalytic H2 generation

Abstract

Green hydrogen production by photocatalytic water splitting offers a promising way to solve environment and energy issues. Conjugated polymer nanostructures (CPNs), with highly π-conjugated structures, have been demonstrated as a new class of photocatalysts. However, pristine CPNs show poor photocatalytic activity for hydrogen generation owing to fast charge carrier recombination and sluggish kinetics. The investigation of application of polypyrrole in photocatalytic hydrogen generation is also rare. Here, we report the surface modification of polypyrrole nanostructures (NSs) with Pt- and Ni-based nanoparticles for photocatalytic hydrogen evolution. PPy nanostructures (NSs) were synthesized using lamellar mesophases as soft templates. The PPy-NSs were modified with mono- and bimetallic (Pt, Ni, Pt–Ni) co-catalyst nanoparticles induced by radiolysis. The prepared Pt-PPy, Ni-PPy and PtNi-PPy exhibit excellent photocatalytic activity for H₂ generation and a synergistic effect is obtained with co-modification with Pt and Ni. The effects of the nature of the metal precursors and the loading ratio were studied. We show that the loading rate of co-catalysts is crucial for H₂ generation, and an excess of co-catalyst can drastically decrease the activity. The composite photocatalyst Pt-Ni-PPy nanostructures are very active and stable with cycling. Our results indicate that modified CPNs with mono- and bimetallic NPs are promising photocatalysts for hydrogen evolution.