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Electrocatalytic Properties of Binuclear Cu(II) Fused Porphyrins for Hydrogen Evolution
journal contribution
posted on 2018-08-14, 00:00 authored by Diana Khusnutdinova, Brian L. Wadsworth, Marco Flores, Anna M. Beiler, Edgar A. Reyes Cruz, Yegor Zenkov, Gary F. MooreBinuclear
copper(II) porphyrins in which two copper(II) porphyrin
macrocycles are doubly fused at the meso-beta positions
are shown to be active electrocatalysts for the hydrogen evolution
reaction (2H+ + 2e– → H2). Structural characterization, including use of electron paramagnetic
resonance and X-ray photoelectron spectroscopies, verifies the fused
species contains two copper(II) metal centers in its resting state.
In comparison to the nonfused copper(II) porphyrin complex, the fused
species is reduced at significantly less applied bias potentials (ΔE1/2 ∼ 570 mV for the first reduction
process). Electrochemical characterization in the presence of substrate
protons confirms the production of hydrogen with near-unity Faradaic
efficiency, and kinetic analysis shows the catalyst achieves a maximum
turnover frequency above 2 000 000 s–1. The enhancement in catalytic performance over analogous nonfused
copper(II) porphyrins indicates extended macrocycles provide an advantageous
structural motif and design element for preparing electrocatalysts
that activate small molecules of consequence to renewable energy.