Selective Alcohol Dehydrogenation
and Hydrogenolysis
with Semiconductor-Metal Photocatalysts: Toward Solar-to-Chemical
Energy Conversion of Biomass-Relevant Substrates
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Abstract
Photocatalytic conversion of biomass is a potentially
transformative
concept in renewable energy. Dehydrogenation and hydrogenolysis of
biomass-derived alcohols can produce renewable fuels such as H<sub>2</sub> and hydrocarbons, respectively. We have successfully used
semiconductor-metal heterostructures for sunlight-driven dehydrogenation
and hydrogenolysis of benzyl alcohol. The heterostructure composition
dictates activity, product distribution, and turnovers. A few metal
(M = Pt, Pd) islands on the semiconductor (SC) surface significantly
enhance activity and selectivity and also greatly stabilize the SC
against photoinduced etching and degradation. Under selected conditions,
CdS-Pt favors dehydrogenation (H<sub>2</sub>) over hydrogenolysis
(toluene) 8:1, whereas CdS<sub>0.4</sub>Se<sub>0.6</sub>-Pd favors
hydrogenolysis over dehydrogenation 3:1. Photochemically generated,
surface-adsorbed hydrogen is useful in tandem catalysis, for example,
via transfer hydrogenation. We expect this work will lead to new paradigms
for sunlight-driven conversions of biomass-relevant substrates
