Photo-bioelectrocatalytic CO2 reduction for a circular energy landscape

Abstract

<h2>Summary</h2> Actualizing the theoretical potential of photoelectrocatalysis for energy-intensive CO₂ reduction, in order to deliver a circular energy economy, is an ongoing research venture. Photobioelectrocatalysis incorporates biological entities that have evolved over billions of years for efficient light harvesting, photo-induced charge separation, and/or sustainable and selective formation of complex, high-energy products under mild conditions. While most existing photobioelectrocatalytic CO₂ reduction systems are nature-inspired or biomimetic, their performances are limited in terms of stability and efficiency. Effective and efficient photo-bioelectrocatalytic CO₂ reduction system design requires incisive integration of multidisciplinary approaches. Biohybrids, which amalgamate the superior features of respectively biotic and abiotic photoelectrocatalytic systems and utilize advances in materials and synthetic chemistry, synthetic biology, etc. to alleviate recurring limitations, are a pliable tool to navigate this system design. This work broadly summarizes existing photo-bioelectrocatalytic CO₂ reduction technologies and their overarching limitations in terms of performance and prospective improvements required in order to facilitate broader applicability. Therein, crucial factors influencing the performance of these biohybrids, such as the type biological catalyst, band gap of photosensitizers, compatibility, and interfacing between biotic – abiotic units, structure, and performance of the overall cell, such as the complimentary half-cell reaction, pH are discussed. Persisting limitations with the increasing sophistication of biohybrid designs include the intricacy of modulating multivariant systems, intermittency of solar energy, poor electrochemical communication across biotic-abiotic interfaces, limited CO₂ dissolution, and other complications overarchingly shared with microbial electrosynthesis and electrocatalytic CO₂ reduction.