*Review* **Membrane Protein Modified Electrodes in Bioelectrocatalysis**

#### **Huijie Zhang** † **, Rosa Catania** † **and Lars J. C. Jeuken \***

School of Biomedical Sciences and the Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; H.Zhang6@leeds.ac.uk (H.Z.); R.Catania@leeds.ac.uk (R.C.)

**\*** Correspondence: L.J.C.Jeuken@leeds.ac.uk; Tel.: +44-113-343-3829

† These authors have contributed equally.

Received: 18 November 2020; Accepted: 3 December 2020; Published: 6 December 2020

**Abstract:** Transmembrane proteins involved in metabolic redox reactions and photosynthesis catalyse a plethora of key energy-conversion processes and are thus of great interest for bioelectrocatalysisbased applications. The development of membrane protein modified electrodes has made it possible to efficiently exchange electrons between proteins and electrodes, allowing mechanistic studies and potentially applications in biofuels generation and energy conversion. Here, we summarise the most common electrode modification and their characterisation techniques for membrane proteins involved in biofuels conversion and semi-artificial photosynthesis. We discuss the challenges of applications of membrane protein modified electrodes for bioelectrocatalysis and comment on emerging methods and future directions, including recent advances in membrane protein reconstitution strategies and the development of microbial electrosynthesis and whole-cell semi-artificial photosynthesis.

**Keywords:** membrane protein; bioelectrocatalysis; electrode modification; biofuel cells; photosynthesis; liposomes; hybrid vesicles; microbial electrosynthesis
