Enhancement of hydrogen production using photoactive nanoparticles on a photochemically inert photonic macroporous support.

The propagation of light in photonic materials can be modified to increase the probability of photon absorption. Here we report the synthesis of composite materials comprising a photochemically inert photonic macroporous ZrO2 support decorated with photocatalytically active CdS nanoparticles. The relative energies of valence and conduction bands restrict photon absorption and catalysis to the CdS nanoparticles. The generation of hydrogen from water under visible light illumination (>400 nm) has been studied as a function of the photonic support. A maximum 4.7 fold enhancement in hydrogen production is observed compared to a non-photonic support when the absorption band of the CdS nanoparticles partially overlaps with the blue edge of the photonic ZrO2 stop band. This general strategy supports the independent optimization of optical and photochemical processes to increase the overall conversion efficiency of solar to chemical energy.