Visible-Light-Driven Photocatalytic H ₂ Production Using Composites of Co–Al Layered Double Hydroxides and Graphene Derivatives

Abstract

The direct conversion of solar energy into chemical energy represents an enormous challenge for current science. One of the commonly proposed photocatalytic systems is composed of a photosensitizer (PS) and a catalyst, together with a sacrificial electron donor (ED) when only the reduction of protons to H ₂ is addressed. Layered double hydroxides (LDH) have emerged as effective catalysts. Herein, two Co–Al LDH and their composites with graphene oxide (GO) or graphene quantum dots (GQD) have been prepared by coprecipitation and urea hydrolysis, which determined their structure and so their catalytic performance, giving H ₂ productions between 1409 and 8643 μmol g ^–1 using a ruthenium complex as PS and triethanolamine as ED at 450 nm. The influence of different factors, including the integration of both components, on their catalytic behavior, has been studied. The proper arrangement between the particles of both components seems to be the determining factor for achieving a synergistic interaction between LDH and GO or GQD. The novel Co–Al LDH composite with intercalated GQD achieved an outstanding catalytic efficiency (8643 μmol H ₂ g ^–1) and exhibited excellent reusability after 3 reaction cycles, thus representing an optimal integration between graphene materials and Co–Al LDH for visible light driven H ₂ photocatalytic production.

Abstract

Several composites of Co−Al LDH and graphene derivatives have been used as catalysts for visible-light-driven H ₂ production. The factors that allow a proper integration of both components to manifest in a synergistic effect, enhancing the activity of pristine LDH, have been investigated.