Nanostructured Materials for Solar Fuels Production: Synthesis, Characterization, and Evaluation

Open Access
Author:
Read Rodríguez, Carlos G.
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 14, 2016
Committee Members:
  • Raymond Edward Schaak, Dissertation Advisor
  • Raymond Edward Schaak, Committee Chair
  • Lasse Jensen, Committee Member
  • Benjamin James Lear, Committee Member
  • Michael Anthony Hickner, Outside Member
Keywords:
  • phosphides
  • hydrogen evolution
  • HER
  • OER
  • nanoparticles
  • electrochemistry
  • electrocatalysis
  • earth-abundant
  • synthesis
  • hybrid
  • heterostructure
Abstract:
Hydrogen gas obtained by electrochemical and photoelectrochemical water splitting has long been proposed as a clean and sustainable alternative to hydrocarbon fuels. While noble metals such as Pt and Ir, are capable of splitting water at low overpotentials, the widespread implementation of inexpensive solar-driven water-splitting systems and electrolyzers requires, among other things, the development of robust, efficient, and abundant alternatives to noble metal catalysts. Recently, transition metal phosphides (MxPy) have been recognized as a promising class of Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER), capable of operating with low overpotentials at benchmark current densities while sustaining high stabilities even in harsh conditions. This dissertation describes the progress that has been made in this field and aims to provide helpful insights into the synthesis, characterization and electrochemical testing of transition metal phosphides, and electrocatalysts in general. In particular, it highlights our work on the identification of iron phosphide (FeP), in the form of monodisperse and hollow colloidal nanocrystals, as a highly active HER catalysts in acidic and neutral aqueous solutions. It also discusses the development of more scalable approaches to the preparation of these materials directly onto the surface of current collectors and photoelectrodes, while maintaining high electrocatalytic activities for both the hydrogen and oxygen evolution reactions. Finally, we present new synthetic approaches to higher-order colloidal hybrid nanoparticles based on supersaturation-precipitation strategies, which could open the door to nanostructures of relevance to photocatalytic fuels production.