Covalency-reinforced oxygen evolution reaction catalyst

Abstract

The oxygen evolution reaction that occurs during water oxidation is of considerable importance as an essential energy conversion reaction for rechargeable metal–air batteries and direct solar water splitting. Cost-efficient ABO3 perovskites have been studied extensively because of their high activity for the oxygen evolution reaction; however, they lack stability, and an effective solution to this problem has not yet been demonstrated. Here we report that the Fe4+-based quadruple perovskite CaCu3Fe4O12 has high activity, which is comparable to or exceeding those of state-of-the-art catalysts such as Ba0.5Sr0.5Co0.8Fe0.2O3−δ and the gold standard RuO2. The covalent bonding network incorporating multiple Cu2+ and Fe4+ transition metal ions significantly enhances the structural stability of CaCu3Fe4O12, which is key to achieving highly active long-life catalysts.

Exceptional electrocatalytic oxygen evolution via tunable charge transfer interactions in La0.5Sr1.5Ni1−xFexO4±δ Ruddlesden-Popper oxides

“…SrCoO 2.7 and LaNiO 3 were synthesized via a coprecipitation method previously reported elsewhere 13,46 in which A and B-site nitrate salts in a 1:1 ratio were dissolved in a 1 wt% solution of TMAOH containing an equimolar amount of TPAB to the total moles of metal cations in order to form mixed metal hydroxide precursor particles. These solutions were flash-frozen on a rotating metal drum that had been cooled to cryogenic temperatures and was collected before lyophilization to remove water.…”

“…Iodometric titrations were performed following the procedure referenced above 13 . In this procedure 3 mL of 2 M KI solution that had previously been deoxygenated were combined in a flask with 15–20 mg of perovskite and stirred for 3 min under argon, after which 25 mL of 1 M HCl was added to dissolve the perovskite.…”

“…Importantly, the ability to substitute elements of varying valence, electronegativity, or ionic size into A- and B-site directly influences the resultant properties of these catalysts 1,12 . An example of this was the substitution of Cu into the A-site of the quadruple perovskite CaCu 3 Fe 4 O 12 to increase stability of the catalyst 13 . Recently, we demonstrated that highly covalent Co 3 d –O 2 p bonding in SrCoO 2.7 improved OER activity via a more energetically favorable lattice oxygen mediated (LOM) reaction pathway, consistent with prior reports and theory 14–16 .…”

Factors Controlling the Redox Activity of Oxygen in Perovskites: From Theory to Application for Catalytic Reactions

“…For instance, Yagi and coworkers stabilized using high pressure synthesis Fe 4+ into the charge transfer quadrupole perovskite CaCu 3 Fe 4 O 12 and demonstrated its large OER activity [94]. Owing to the short O-O bond distance (≈2.6 Å) stabilized by the use of high pressure synthesis, the direct O-O bond formation between two neighboring lattice oxygen was proposed to be a possible reaction intermediate for the formation of gaseous oxygen.…”

Undoped and Ni-Doped CoOx Surface Modification of Porous BiVO4 Photoelectrodes for Water Oxidation

“…25 Surface modification of photoanodes with OER catalysts is an effective approach to reduce the photocurrent onset potential because it can enhance water oxidation kinetics and reduce external bias. [25][26][27][28][29] For BiVO4, the surface modification should perform OER in the appropriate pH range and also reduce the hole recombination at the BiVO4/catalyst interface. There has been extensive work on the integration of BiVO4 with OER catalysts (see Table S1 for details, Supporting Information).…”