Vitamin B12 on Graphene for Highly Efficient CO2 Electroreduction
Vitamin B12 on Graphene for Highly Efficient CO2 Electroreduction
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DOI：
10.1021/acsami.0c10125
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发表时间：
2020-09-16
影响因子：
9.5
通讯作者：
Das, Biswanath
中科院分区：
文献类型：
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作者：
Jia, Chen;Ching, Karin;Das, Biswanath
结合均相和非均相催化系统的优势已经成为电化学CO2还原的一种很有前途的策略，尽管开发强大的、活性的、产品选择性的、容易获得的催化剂仍然是一个主要的挑战。在此，我们报道了钴和含维生素B-12的苯并咪唑固定在还原氧化石墨烯（rGO）表面上催化CO2的电还原。该混合系统具有天然丰富的分子催化剂，在水溶液缓冲溶液（pH 7.2）中产生具有高选择性和恒定电流密度的CO超过10小时。在过电位690 mV下，CO分电流密度（j(CO)）为6.24 mA cm(-2)，转换频率（TOF）高达28.6 s(-1)， CO2转化为CO的法拉第效率（FE）为94.5%。在较高的过电位（790 mV）下，该体系可以获得较高的j(CO) （13.6 mA cm(-2)）和TOF (52.4 s(-1))，而不会影响CO生成的产物选择性（类似于94%）。我们的实验结果与密度泛函理论（DFT）研究相证实，以了解共价连接和氧化还原活性苯并咪唑单元的影响。据我们所知，这是第一个将天然丰富的维生素固定在导电表面以实现高效二氧化碳电还原的例子。
Combining the advantages of homogeneous and heterogeneous catalytic systems has emerged as a promising strategy for electrochemical CO2 reduction although developing robust, active, product-selective, and easily available, catalysts remains a major challenge. Herein, we report the electroreduction of CO2 catalyzed by cobalt and benzimidazole containing Vitamin B-12 immobilized on the surface of reduced graphene oxide (rGO). This hybrid system with a naturally abundant molecular catalyst produces CO with high selectivity and a constant current density in an aqueous buffer solution (pH 7.2) for over 10 h. A Faradaic efficiency (FE) of 94.5% was obtained for converting CO2 to CO at an overpotential of 690 mV with a CO partial current density (j(CO)) of 6.24 mA cm(-2) and a turnover frequency (TOF) of up to 28.6 s(-1). A higher j(CO) (13.6 mA cm(-2)) and TOF (52.4 s(-1)) can be achieved with this system at a higher overpotential (790 mV) without affecting the product selectivity (similar to 94%) for CO formation. Our experimental findings are corroborated with density functional theory (DFT) studies to understand the influence of the covalently attached and redox-active benzimidazole unit. To the best of our knowledge, this is the first example of naturally abundant vitamin being immobilized on a conductive surface for highly efficient CO2 electroreduction.