Sekar Narendran, Umasankar Yogeswaran, Ramasamy Ramaraja P
Nano Electrochemistry Laboratory, College of Engineering, The University of Georgia, Athens, GA 30602, USA.
Phys Chem Chem Phys. 2014 May 7;16(17):7862-71. doi: 10.1039/c4cp00494a.
Cyanobacteria possess unique and exciting features among photosynthetic microorganisms for energy conversion applications. This study focuses on production of direct electricity using a cyanobacterium called Nostoc sp. (NOS) as a photo-biocatalyst immobilized on carbon nanotubes on the anode of photo-bioelectrochemical cells. By illuminating with light (intensity 76 mW cm(-2)) the NOS immobilized on a carbon nanotube (CNT) modified electrode generated a photocurrent density of 30 mA m(-2) at 0.2 V (vs. Ag/AgCl). The contribution of different photosynthetic pigments in NOS to the light capture was analyzed and chlorophyll-a was found to be the major contributor to light capture followed by phycocyanin. Further investigation using a set of inhibitors revealed that the electrons were redirected predominantly from PSII to the CNT through the plastoquinone pool and quinol oxidase. A rudimentary design photosynthetic electrochemical cell has been constructed using NOS/CNT on the anode and laccase/CNT on the cathode as catalysts. The cell generated a maximum current density of 250 mA m(-2) and a peak power density of 35 mW m(-2) without any mediator. By the addition of 1,4-benzoquinone as a redox mediator, the electricity generation capability was significantly enhanced with a current density of 2300 mA m(-2) and a power density of 100 mW m(-2). The power densities achieved in this work are the highest among 'non-engineered' cyanobacteria based electrochemical systems reported to date.
蓝细菌在用于能量转换应用的光合微生物中具有独特且令人兴奋的特性。本研究聚焦于使用一种名为念珠藻属（NOS）的蓝细菌作为光生物催化剂来生产直流电，该催化剂固定在光生物电化学电池阳极的碳纳米管上。通过用强度为76 mW cm⁻²的光照射，固定在碳纳米管（CNT）修饰电极上的NOS在0.2 V（相对于Ag/AgCl）时产生了30 mA m⁻²的光电流密度。分析了NOS中不同光合色素对光捕获的贡献，发现叶绿素a是光捕获的主要贡献者，其次是藻蓝蛋白。使用一组抑制剂进行的进一步研究表明，电子主要通过质体醌库和醌氧化酶从光系统II重新导向CNT。构建了一个初步设计的光合电化学电池，在阳极使用NOS/CNT，在阴极使用漆酶/CNT作为催化剂。该电池在没有任何介质的情况下产生了250 mA m⁻²的最大电流密度和35 mW m⁻²的峰值功率密度。通过添加1,4 - 苯醌作为氧化还原介质，发电能力显著增强，电流密度达到2300 mA m⁻²，功率密度达到100 mW m⁻²。在这项工作中实现的功率密度是迄今为止报道的基于“非工程化”蓝细菌的电化学系统中最高的。
