In situ addition of graphitic carbon into a NiCo2O4/CoO composite: enhanced catalysis toward the oxygen evolution reaction

Srinivasa N; Shreenivasa L; Prashanth S Adarakatti; Jack P Hughes; Samuel J Rowley-Neale; Craig E Banks; Ashoka S

doi:10.1039/c9ra05195c

In situ addition of graphitic carbon into a NiCo₂O₄/CoO composite: enhanced catalysis toward the oxygen evolution reaction

RSC Adv. 2019 Aug 12;9(43):24995-25002. doi: 10.1039/c9ra05195c. eCollection 2019 Aug 8.

Authors

Srinivasa N¹, Shreenivasa L¹, Prashanth S Adarakatti², Jack P Hughes^{3

4}, Samuel J Rowley-Neale^{3

4}, Craig E Banks^{3

4}, Ashoka S¹

Affiliations

¹ Department of Chemistry, School of Engineering, Dayananda Sagar University Bangalore India ashok022@gmail.com +91 8049092924.
² PG Department of Chemistry, KLE's PC Jabin Science College Hubballi India.
³ Faculty of Science and Engineering, Manchester Metropolitan University Chester Street Manchester M1 5GD UK c.banks@mmu.ac.uk S.Rowley-Neale@mmu.ac.uk http://craigbanksresearch.com +44 (0)1612476831 +44 (0)1612471196.
⁴ Manchester Fuel Cell Innovation Centre, Manchester Metropolitan University Chester Street Manchester M1 5GD UK.

Abstract

We present a rapid, environmentally benign one-pot synthesis technique for the production of a NiCo₂O₄/CoO and graphite composite that demonstrates efficient electrocatalysis towards the Oxygen Evolution Reaction (OER), in 1.0 M KOH. The NiCo₂O₄/CoO/graphitic carbon composite that displayed optimal OER catalysis was synthesized by nitrate decomposition in the presence of citric acid (synthesized glycine and sucrose variants displayed inferior electro kinetics towards the OER). Screen-printed electrodes modified with ca. 530 μg cm^-2 of the citric acid NiCo₂O₄/CoO/graphite variant displayed remarkable OER catalysis with an overpotential (η) of +323 mV (vs. RHE) (recorded at 10 mA cm^-2), which is superior to that of IrO₂ (340 mV) and RuO₂ (350 mV). The composite also exhibited a large achievable current density of 77 mA cm^-2 (at +1.5 V (vs. RHE)), a high O₂ turnover frequency of 1.53 × 10^-2 s^-1 and good stability over the course of 500 repeat cycles. Clearly, the NiCo₂O₄/CoO composite has the potential to replace precious metal based catalysts as the anodic material within electrolysers, thereby providing a reduction in the associated costs of hydrogen production via water splitting.