Polymer-modified hydrophilic graphene: A promotor to photocatalytic hydrogen evolution for in situ formation of core@shell cobalt nanocomposites

To improve dispersibility of graphene for photocatalytic hydrogen evolution in water, hydrophilic reduced graphene GJ600 was simply prepared in situ through one-pot ring-opening reaction between graphene oxide precursor and industrial Jeffamine M-600 polyetheramine, which shows good dispersibility in an aqueous solution, and strong affinity toward metal ions. These features have been integrated to construct an enhanced photocatalytic H-2 evolution system, in which eosin Y was employed as the photosensitizer, triethanolamine (TEOA) as the sacrificial electron donor, low cost Co2+ as the catalytic precursor. During irradiation by visible light, the aggregation of catalytic centre and graphene is greatly suppressed, and similar to 3.78 times enhancement of photocatalytic H-2 evolution is achieved as compared with the system in the absence of graphene. By using HRTEM, XRD, XPS, ICP-AES, as well as spectroscopic and electrochemical approaches, an in situ formed core@shell composites of Co-x/Co (TEOA)(y)(GJ600)(z), on the basal plane of the graphene sheets is verified as the real catalytic structure. This polymer-modified graphene not only help with the multi-electron transfer between photosensitizer and the catalytic metal centre but also facilitate the formation of this unique core@shell nanocomposites for efficient photocatalytic H-2 evolution. (C) 2015 Elsevier B.V. All rights reserved.