Robust and efficient electrocatalyst for water oxidation based on 4,4′-oxybis(benzoate)-linked copper(II) hydroxido layers

An uncommon copper(II) hydroxide layer-based coordination polymer [Cu₃(OH)₄(oba)]_n (1) (oba = 4,4′-oxybisbenzoate) has been synthesized and tested as electro-catalyst for water oxidation under basic conditions. In comparison to classical Cu(OH)₂, 1 exhibits improved thermal stability of up to ca. 350 °C. Chronoamperometry studies indicate that catalyst 1 reaches an anodic current density of 0.1 mA cm⁻² at η = 576 mV; a TOF of 2 × 10⁻³ s⁻¹ at 418 mV overpotential value. The catalyst 1 shows Faradaic efficiency of 95%. Long-term catalytic studies for 10 h at a constant potential of 1.2 V indicate that compound 1 is robust and retains its chemical composition. Infrared spectroscopy, powder X-ray diffraction analysis, X-ray photoelectron spectroscopy and cyclic voltammetry studies of the pristine and post-catalytic compound 1-coated FTO electrodes further confirm that 1 retains its structural integrity throughout the catalytic cycle. Our results represent a proof-of-concept for designing next-generation robust and improved OER electrocatalysts based on earth-abundant metals.