Facile approaches to control catalytic activity of viral-templated palladium nanocatalysts for dichromate reduction

We present two facile procedures to control catalytic activity of viral-templated palladium (Pd) nanocatalysts. Specifically, tunable and selective surface assembly of genetically modified Tobacco Mosaic Virus (TMV1cys) templates is exploited to control the loading of Pd nanocatalysts on solid substrates via preferential electroless deposition. In the first method, the surface density of Pd–TMV complexes is controlled by varying the concentration of TMV solution for surface assembly. Apparent surface density of Pd–TMV complexes from AFM images correlated well with the Pd loading observed via XPS and the catalytic activity in dichromate reduction, an important environmental remediation reaction for detoxification of abundant inorganic wastes. In the second method, the Pd catalyst loading is controlled by varying the gold surface area on patterned silicon chips. The catalytic activity of these chips correlated well with the surface area, further indicating control over the location of active Pd catalysts via selective surface assembly of viral templates. We envision that our approach to control the TMV surface density and specific location of catalysts by exploiting biologically derived template materials can be extended to other biotemplates and/or reaction systems via a wide range of tunable surface patterning/assembly techniques.