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Poor electrochemical communication between biocatalysts and electrodes is a ubiquitous limitation to bioelectrocatalysis efficiency. An extensive library of polymers has been developed to modify biocatalyst-electrode interfaces to alleviate this limitation. As such, conducting redox polymers (CRPs) are a versatile tool with high structural and functional tunability. While charge transport in CRPs is well characterized, the understanding of charge transport mechanisms facilitated by CRPs within decisively complex photobioelectrocatalytic systems remains very limited. This study is a comprehensive analysis that dissects the complex kinetics of photobioelectrodes into fundamental blocks based on rational assumptions, providing a mechanistic overview of charge transfer during photobioelectrocatalysis. We quantitatively compare two biohybrids of metal-free unbranched CRP (polydihydroxy aniline) and photobiocatalyst (intact chloroplasts), formed utilizing two deposition strategies ( “mixed” and “layered” depositions). The superior photobioelectrocatalytic performance of the “ layered” biohybrid compared to the “ mixed” counterpart is justified in terms of rate ( D app ), thermodynamic and kinetic barriers (H ≠ , E a ), frequency of molecular collisions ( D 0 ) during electron transport across depositions, and rate and resistance to heterogeneous electron transfer ( k 0 , R CT ). Our results indicate that the primary electron transfer mechanism across the biohybrids, constituting the unbranched CRP, is thermally activated intra- and inter-molecular electron hopping, as opposed to a non-thermally activated polaron transfer model typical for branched CRP- or conducting polymer (CP)-containing biohybrids in literature. This work underscores the significance of subtle interplay between CRP structure and deposition strategy in tuning the polymer-catalyst interfaces, and the branched/unbranched structural classification of CRPs in the bioelectrocatalysis context. 

Abstract Bioelectrocatalytic synthesis is the conversion of electrical energy into value‐added products using biocatalysts. These methods merge the specificity and selectivity of biocatalysis and energy‐related electrocatalysis to address challenges in the sustainable synthesis of pharmaceuticals, commodity chemicals, fuels, feedstocks and fertilizers. However, the specialized experimental setups and domain knowledge for bioelectrocatalysis pose a significant barrier to adoption. This review introduces key concepts of bioelectrosynthetic systems. We provide a tutorial on the methods of biocatalyst utilization, the setup of bioelectrosynthetic cells, and the analytical methods for assessing bioelectrocatalysts. Key applications of bioelectrosynthesis in ammonia production and small‐molecule synthesis are outlined for both enzymatic and microbial systems. This review serves as a necessary introduction and resource for the non‐specialist interested in bioelectrosynthetic research. 

Abstract The development of electrochemical catalytic conversion of 5‐hydroxymethylfurfural (HMF) has recently gained attention as a potentially scalable approach for both oxidation and reduction processes yielding value‐added products. While the possibility of electrocatalytic HMF transformations has been demonstrated, this growing research area is in its initial stages. Additionally, its practical applications remain limited due to low catalytic activity and product selectivity. Understanding the catalytic processes and design of electrocatalysts are important in achieving a selective and complete conversion into the desired highly valuable products. In this Minireview, an overview of the most recent status, advances, and challenges of oxidation and reduction processes of HMF was provided. Discussion and summary of voltammetric studies and important reaction factors (e. g., catalyst type, electrode material) were included. Finally, biocatalysts (e. g., enzymes, whole cells) were introduced for HMF modification, and future opportunities to combine biocatalysts with electrochemical methods for the production of high‐value chemicals from HMF were discussed.