Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nat Mater. 2022 Jun;21(6):673-680. doi: 10.1038/s41563-022-01199-0. Epub 2022 Feb 24.
The oxygen evolution reaction is central to making chemicals and energy carriers using electrons. Combining the great tunability of enzymatic systems with known oxide-based catalysts can create breakthrough opportunities to achieve both high activity and stability. Here we report a series of metal hydroxide-organic frameworks (MHOFs) synthesized by transforming layered hydroxides into two-dimensional sheets crosslinked using aromatic carboxylate linkers. MHOFs act as a tunable catalytic platform for the oxygen evolution reaction, where the π-π interactions between adjacent stacked linkers dictate stability, while the nature of transition metals in the hydroxides modulates catalytic activity. Substituting Ni-based MHOFs with acidic cations or electron-withdrawing linkers enhances oxygen evolution reaction activity by over three orders of magnitude per metal site, with Fe substitution achieving a mass activity of 80 A [Formula: see text] at 0.3 V overpotential for 20 h. Density functional theory calculations correlate the enhanced oxygen evolution reaction activity with the MHOF-based modulation of Ni redox and the optimized binding of oxygenated intermediates.
氧析出反应对于利用电子来制造化学物质和能量载体至关重要。将酶系统的巨大可调性与已知的基于氧化物的催化剂相结合，可以创造突破性的机会，实现高活性和稳定性。在这里，我们报告了一系列通过将层状氢氧化物转化为使用芳族羧酸酯连接体交联的二维片而合成的金属氢氧化物-有机骨架（MHOF）。MHOF 作为氧析出反应的可调催化平台，相邻堆叠连接体之间的π-π相互作用决定了稳定性，而氢氧化物中过渡金属的性质调节了催化活性。用酸性阳离子或吸电子连接体取代基于 Ni 的 MHOF 可使每个金属位点的氧析出反应活性提高三个数量级以上，Fe 取代在 0.3 V 过电势下 20 h 内的质量活性达到 80 A [Formula: see text]。密度泛函理论计算将增强的氧析出反应活性与基于 MHOF 的 Ni 氧化还原调节和含氧中间体的优化结合联系起来。
