Date of Award:

5-2017

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Chemistry and Biochemistry

Committee Chair(s)

Yujie Sun

Committee

Yujie Sun

Committee

Lisa M. Berreau

Committee

Lance C. Seefeldt

Abstract

Solar energy is a carbon-neutral and renewable energy resource. Its nature of intermittence and unequal distribution requires efficient solar energy capture, conversion, and storage. Solar-driven water splitting to produce hydrogen and oxygen is widely considered as an appealing approach to meet this goal, in which hydrogen acts as a green energy carrier. Water splitting consists of two redox half reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Both reactions involve the transfer of multiple electrons and protons and possess high energy barriers to proceed at appreciable rates, hence catalysts are needed.

A large number of HER and OER catalysts employ expensive metals, such as Pt, Ru, and Ir, but the associated scarce and cost prohibit their wide application. Solid-state catalysts employing earth-abundant elements have also been reported to show catalytic performance for water splitting under various conditions. Most research efforts have been devoted to developing non-precious HER and OER catalysts in acidic and basic media, respectively. The incompatibility of electrolytes makes it difficult to couple HER and OER catalysts to achieve overall water splitting. Taking into account of the vulnerability of most 1st-row transition metal-based OER catalysts in acidic solution and the much larger overpotential loss of OER than that of HER, we reasoned that developing bifunctional catalysts that operate in basic solution will be a promising strategy for overall water splitting with high efficiency.

The research results presented in this thesis showcase our achievements in developing low-cost electrocatalyts for HER and OER. Our research particularly focused on the 1st-row transition metal-based sulfides and phosphides, which exhibited excellent activity and stability for electrocatalytic water splitting.

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