Catalytic four-electron reduction of O₂ to water is one of the most extensively studied electrochemical reactions due to O₂ exceptional availability and high O₂/H₂O redox potential, which may in particular allow highly energetic reactions in fuel cells. To circumvent the use of expensive and inefficient Pt catalysts, multicopper oxidases (MCOs) have been envisioned because they provide efficient O₂ reduction with almost no overpotential. MCOs have been used to elaborate enzymatic biofuel cells (EBFCs), a subclass of fuel cells in which enzymes replace the conventional catalysts. A glucose/O₂ EBFC, with a glucose oxidizing anode and a O₂ reducing MCO cathode, could become the in vivo source of electricity that would power sometimes in the future integrated medical devices. This review covers the challenges and advances in the electrochemistry of MCOs and their use in EBFCs with a particular emphasis on the last 6 years. First basic features of MCOs and EBFCs are presented. Clues provided by electrochemistry to understand these enzymes and how they behave once connected at electrodes are described. Progresses realized in the development of efficient biocathodes for O₂ reduction relying both on direct and mediated electron transfer mechanism are then discussed. Some implementations in EBFCs are finally presented.

中文翻译：

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酶促生物燃料电池中的O ₂减少

O ₂催化四电子还原为水是由于O ₂出众的可用性和高O ₂ / H ₂ O氧化还原电势而在水中进行的最广泛研究的电化学反应之一，这尤其可能使燃料电池中发生高能反应。为了避免使用昂贵和低效的Pt催化剂，人们已经想到了多铜氧化酶（MCO），因为它们可以有效地还原O ₂，几乎没有超电势。MCO已用于制造酶促生物燃料电池（EBFC），这是燃料电池的一类，其中的酶替代了常规催化剂。葡萄糖/ O ₂ EBFC，具有葡萄糖氧化阳极和O ₂减少MCO阴极，可能会成为体内电力来源，将来有时会为集成医疗设备供电。这篇综述涵盖了MCO电化学及其在EBFC中的使用方面的挑战和进展，特别是在过去的6年中。介绍了MCO和EBFC的第一个基本特征。描述了电化学提供的线索，以了解这些酶及其在电极上连接后的行为。然后讨论了直接和介导的电子转移机制在开发有效的O ₂还原生物阴极方面取得的进展。最后介绍了EBFC中的一些实现。