Water oxidation by a nickel-glycine catalyst.
Water oxidation by a nickel-glycine catalyst.
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DOI：
10.1021/ja504282w
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发表时间：
2014-07
影响因子：
15
通讯作者：
Dong Wang;G. Ghirlanda;James P. Allen
中科院分区：
文献类型：
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作者：
Dong Wang;G. Ghirlanda;James P. Allen
太阳能的利用需要一种有效的手段将其储存为化学能。在生物启发的人工光合作用中，光能可用于驱动水氧化，但需要从水中产生分子氧的催化剂，以避免过度的驱动潜力。在本文中，我们证明了利用地球丰富的Ni与甘氨酸结合的新型络合物作为有效催化剂的实用性，在pH 11的电流密度为1 mA/cm（2）时具有0.475 ± 0.005 V的适度过电位。催化需要胺部分的存在，其中甘氨酸最可能以4：1的摩尔比与Ni配位。通过测量氧浓度的变化来验证在高电位下分子氧的产生，产生60 ± 5%的法拉第效率。催化物种最有可能是通过电化学氧化形成的非均相Ni-氢氧化物。该Ni物质可以实现持续至少10小时的4 mA/cm（2）的电流密度。基于所观察到的电流幅度和氧化/还原峰的pH依赖性，催化机理是电子-质子耦合过程。
The utilization of solar energy requires an efficient means for its storage as chemical energy. In bioinspired artificial photosynthesis, light energy can be used to drive water oxidation, but catalysts that produce molecular oxygen from water are needed to avoid excessive driving potentials. In this paper, we demonstrate the utility of a novel complex utilizing earth-abundant Ni in combination with glycine as an efficient catalyst with a modest overpotential of 0.475 ± 0.005 V at a current density of 1 mA/cm(2) at pH 11. Catalysis requires the presence of the amine moiety with the glycine most likely coordinating the Ni in a 4:1 molar ratio. The production of molecular oxygen at a high potential is verified by measurement of the change in oxygen concentration, yielding a Faradaic efficiency of 60 ± 5%. The catalytic species is most likely a heterogeneous Ni-hydroxide formed by electrochemical oxidation. This Ni species can achieve a current density of 4 mA/cm(2) that persists for at least 10 h. Based upon the observed pH dependence of the current amplitude and oxidation/reduction peaks, the catalytic mechanism is an electron-proton coupled process.