Graphene/TiO2 hydrogel: a potential catalyst to hydrogen evolution reaction

Abstract

In this study, graphene was synthesized from graphite. Graphite was oxidized via modified Hummer's method and sonicated to form graphene oxide (GO). Infrared spectroscopy revealed the successful oxidation of graphite by the emergence of oxygen functionalities. The spectrum of GO showed peaks at 3270, 1629, 1227 and 1096 cm −1 , indicating O-H, C=O, C-OH and CO -C functional groups, respectively. Graphene hydrogels were prepared by the addition of L-ascorbic acid to GO suspensions and subsequent heating at 90 • C. Composite hydrogels of graphene and titanium (IV) oxide (TiO 2) were synthesized with various TiO 2 to GO mass ratios. Composites were applied to photocatalytic hydrogen evolution reaction (HER) and the hydrogen gas produced was analysed by gas chromatography with thermal conductivity detector. Highest HER yield was 66.00% H 2 .

Conjugated Polymer Hydrogel Photocatalysts with Expandable Photoactive Sites in Water

“…Hydrophilic hydrogel networks can hold huge amount of water by structural swelling, and such a volume change provides inner channels to accommodate guest structures. − In this regard, the photocatalysts are loaded on the hydrogel materials to make water-compatible heterogeneous photocatalytic systems. Recent examples include hydrogels with immobilized titanium oxide (TiO 2 ), − CdS, porphyrin, carbon nitride, , graphene hydrogels with TiO 2 , and self-assembled hydrogel with Ni catalyst . The hydrogel photocatalysts in such composite structures, however, may have to compromise their photocatalytic activity with hydrophilicity, since the photocatalysts are deeply embedded inside the hydrogel networks, limiting the accessibility to photoactive sites.…”