Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599, United States.
J Am Chem Soc. 2014 May 14;136(19):6854-7. doi: 10.1021/ja502637s. Epub 2014 May 1.
Rapid water oxidation catalysis is observed following electrochemical oxidation of Ru(II)(tpy)(bpz)(OH) to Ru(V)(tpy)(bpz)(O) in basic solutions with added buffers. Under these conditions, water oxidation is dominated by base-assisted Atom Proton Transfer (APT) and direct reaction with OH(-). More importantly, we report here that the Ru(IV)═O(2+) form of the catalyst, produced by 1e(-) oxidation of Ru(II)(tpy)(bpz)(OH2) to Ru(III) followed by disproportionation to Ru(IV)(tpy)(bpz)(O) and Ru(II)(tpy)(bpz)(OH2), is also a competent water oxidation catalyst. The rate of water oxidation by Ru(IV)(tpy)(bpz)(O) is greatly accelerated with added PO4(3-) with a turnover frequency of 5.4 s(-1) reached at pH 11.6 with 1 M PO4(3-) at an overpotential of only 180 mV.
在碱性溶液中加入缓冲剂后，[Ru(II)(tpy)(bpz)(OH)]⁺电化学氧化为[Ru(V)(tpy)(bpz)(O)]³⁺，可观察到快速水氧化催化作用。在这些条件下，水氧化主要由碱辅助原子质子转移（APT）和与 OH⁻的直接反应决定。更重要的是，我们在这里报告，催化剂的 Ru(IV)═O(2+)形式，由[Ru(II)(tpy)(bpz)(OH2)]²⁻经 1e⁻氧化为 Ru(III)，然后歧化为[Ru(IV)(tpy)(bpz)(O)]²⁻和[Ru(II)(tpy)(bpz)(OH2)]²⁻生成，也是一种有效的水氧化催化剂。[Ru(IV)(tpy)(bpz)(O)]²⁻的水氧化速率在加入 PO4(3-)后大大加快，在 pH 11.6 时，在 1 M PO4(3-)存在下，过电位仅为 180 mV，达到 5.4 s⁻¹的周转频率。
