Zhu Heng, Lv Ximei, Wu Yuexu, Wang Wentao, Wu Yuping, Yan Shicheng, Chen Yuhui
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, 211816, Nanjing, China.
School of Physical and Mathematical Sciences, Nanjing Tech University, 211816, Nanjing, China.
Nat Commun. 2024 Oct 14;15(1):8846. doi: 10.1038/s41467-024-53134-3.
Water electro-oxidation to form HO is an important way to produce HO which is widely applied in industry. However, its mechanism is under debate and HO, hydroxyl group adsorbed onto the surface of the electrode, is regarded as an important intermediate. Herein, we study the mechanism of water oxidation to HO at Pt electrode using in-situ Raman spectroscopy and differential electrochemical mass spectroscopy and find peroxide bond mainly originated from the coupling of two CO via a CO intermediate. By quantifying the O isotope in the product, we find that 93% of HO was formed via the CO coupling route and 7% of HO is from OH-CO route. The OH-OH coupling route has a negligible contribution. The comparison of various electrodes shows that the strong adsorption of CO at the electrode surface is essential. Combining with a commercial cathode catalyst to produce HO during oxygen reduction, we assemble a flow cell in which the cathode and anode simultaneously produce HO. It shows a Faradaic efficiency of 150% of HO at 1 A cm with a cell voltage of 2.3 V.
水电氧化生成羟基自由基（HO）是生产羟基自由基的重要途径，其在工业中有着广泛应用。然而，其反应机理仍存在争议，吸附在电极表面的羟基（HO）被视为重要中间体。在此，我们利用原位拉曼光谱和差分电化学质谱研究了铂电极上水电氧化生成羟基自由基的机理，发现过氧键主要源于两个一氧化碳（CO）通过一个CO中间体的偶联。通过对产物中的氧同位素进行定量分析，我们发现93%的羟基自由基是通过CO偶联途径形成的，7%的羟基自由基来自OH-CO途径。OH-OH偶联途径的贡献可忽略不计。对各种电极的比较表明，电极表面对CO的强吸附至关重要。结合商业阴极催化剂在氧还原过程中生成羟基自由基，我们组装了一个流动电池，其中阴极和阳极同时产生羟基自由基。在1 A cm-2的电流密度下，电池电压为2.3 V时，羟基自由基的法拉第效率达到150%。
