Bio-Inspired Heterogeneous Catalytic Cascades

Abstract

Bio-electrochemistry research in our group has been focused on building suitable materials and design of interfaces to accommodate biocatalysts, both enzymatic and microbial for most advantageous utilization in sensing, energy harvesting and water treatment technologies. Over the years we have demonstrated several enabling materials design approaches to address critical challenges in bio-electrocatalysis: facilitating charge transfer through tethering immobilization, enzyme orientation, hierarchically structured nano-materials integrated into device design, immobilization by encapsulation in polymer and silica matrixes and development of hybrid microbial/enzymatic and microbial/platinum group metal-free bio-electrochemical devices. A critical challenge in building complex bio-nano-devices is the ability to combine several catalytic reactions into a “cascade” with channeling as underlying principle for effective multi-step catalysis.1One particularly complex area of our research over the last yeas has been in development of materials solutions for catalytic cascades, which would integrate bio-catalysis with molecular and heterogeneous catalytic steps.2-4We are currently engaged in a large program directed towards bringing together functional catalysts from the most distinctly different types: enzymes, molecular catalyst and metallic nanoparticles into a singular functional interface for realization of cascade reactions catalyzed by all these different species/moieties. We will illustrate the approach by discussing the synthesis of a hybrid enzyme/metal nano-particle/atomically-dispersed nano-material functional catalyst cascade. This bio-inspired catalytic cascade aims to demonstrate the possibility of assembling heterogeneous catalytic reactions in sequence while the catalysts of three dissimilar classes are all immobilized on a 2D nanomaterial (graphene). The paper aims to bring a vision of building bio-electrochemical devices, where enzymatic catalysis will be enhanced by the heterogeneous and molecular one, with all catalytic moieties co-present at a single “designer interface” based on graphene-like carbonaceous material. This material allows ease of integration by printing into a paper-based microfluidic analytical platform designed for a confocal Raman microscope with in situspectro-electrochemical detection.5,6 1. Wheeldon, I., et al., Nature Chemistry,8 (2016) 299–3092. Abdellaoui,S., et al., Chemical Communications, 53(2017) 5368-53713. Xia, L., et al., ACS Energy Letters., 2 (2017) 1435-14384. Perry, A., et al., ChemElectroChem, 4 (2017) 2336-23445. Andersen, N., et al., ChemElectroChem, 6 (2019) 246-2516. Andersen, N., et al., ChemElectroChem, 6 (2019) 2448–2455 Figure 1