Designing novel multinary transition metal selenides as high-efficiency oxygen evolution reaction electrocatalysts and investigating surface properties

”Water splitting has been widely considered to be an efficient way to generate sustainable and renewable energy resources in fuel cells, metal-air batteries and other energy conversion devices. Exploring efficient electrocatalysts to expedite the anodic oxygen evolution reaction (OER) is a crucial task that needs to be addressed to boost the practical application of water splitting. This research focuses on the identification of OER electrocatalysts by systematically designing non-stochiometric mixed transition metal-based selenide OER electrocatalysts through combinatorial electrodeposition and investigation of selenide-based naturally occurring minerals as effective OER electrocatalyst. Paper I describes the study of Ni-Fe-Co selenides as OER catalysts by combinatorial electrodeposition and the best composition (Ni0.25Fe0.68Co0.07)3Se4 with the lowest overpotential. Paper II presents the exploration of Co-Ni-Cu selenide system through combinatorial electrodeposition of 66 different compositions as highly efficient OER electrocatalysts and the best quaternary (Co0.21Ni0.25Cu0.54)3Se2 showing a similar crystal structure as its parent compound Cu3Se2. Paper III introduces the Fe-Co-Cu selenide system investigated through combinatorial electrodeposition, and the optimal quaternary is identified as (Fe0.48Co0.38Cu0.14)Se. Paper IV presents CuCo2Se4 as high-efficiency bifunctional electrocatalyst for full water splitting and conducted DFT calculation of surface dependent OER activity on (100) and (111) facets. Paper V introduces the hydrothermal synthesis of naturally-occurring mineral Tyrrellite Cu(Co0.68Ni0.32)2Se4 as highly-efficient OER electrocatalyst. Paper VI describes three naturally occurring copper selenides (Cu2Se, Cu3Se2 and CuSe2) as OER electrocatalyst and performed DFT calculation to understand their catalytic activity trend”--Abstract, page iv