University of Louisville
Electrocatalyst Decorated Hematite Nanowire Arrays for Photoelectrochemical Water Splitting
Institution
University of Louisville
Faculty Advisor/ Mentor
Mahendra Sunkara
Abstract
One of the greatest issues facing society today is finding a renewable energy source to power our world. Solar power is a leading option. However, storing solar power is one of the leading pitfalls in this field, and one viable option is to store solar power in chemical bonds. For example, hydrogen production using sunlight to split water offers one such possibility. In order to accomplish solar energy conversion to fuels requires the use of semiconductors with appropriate solar light absorption band gap (the amount energy required for conducting electrons) and electrical properties for enabling hydrogen and oxygen evolution reactions from water. Hematite, α-Fe2O3, is a semiconductor that has attracted considerable interest due to its favorable band gap for solar light absorption and low cost. However, hematite suffers from two main disadvantages: the electron diffusion is limited to a few nanometers, when larger diffusion is desired; and the hematite surfaces are not highly catalytic towards electrolysis of water. In this project, we investigated the use of catalysts on the hematite nanowire array to address both challenges. Specifically, nickel particles were created on the hematite nanowire surfaces by applying a solution of nickel (II) nitrate in varying concentrations then exposing the nanowires to atmospheric oxygen plasma. The results have shown that nickel nanoparticles were adhered to the hematite nanowire arrays. In addition, the samples were placed in an oven at high temperatures over long periods of time to enable formation of nickel iron oxide alloy. The hematite nanowire arrays decorated with nickel particles and the iron nickel oxide nanowire samples were characterized for electrocatalysis and photocatalysis using cyclic voltammetry. The physical properties were tested using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX).
Electrocatalyst Decorated Hematite Nanowire Arrays for Photoelectrochemical Water Splitting
One of the greatest issues facing society today is finding a renewable energy source to power our world. Solar power is a leading option. However, storing solar power is one of the leading pitfalls in this field, and one viable option is to store solar power in chemical bonds. For example, hydrogen production using sunlight to split water offers one such possibility. In order to accomplish solar energy conversion to fuels requires the use of semiconductors with appropriate solar light absorption band gap (the amount energy required for conducting electrons) and electrical properties for enabling hydrogen and oxygen evolution reactions from water. Hematite, α-Fe2O3, is a semiconductor that has attracted considerable interest due to its favorable band gap for solar light absorption and low cost. However, hematite suffers from two main disadvantages: the electron diffusion is limited to a few nanometers, when larger diffusion is desired; and the hematite surfaces are not highly catalytic towards electrolysis of water. In this project, we investigated the use of catalysts on the hematite nanowire array to address both challenges. Specifically, nickel particles were created on the hematite nanowire surfaces by applying a solution of nickel (II) nitrate in varying concentrations then exposing the nanowires to atmospheric oxygen plasma. The results have shown that nickel nanoparticles were adhered to the hematite nanowire arrays. In addition, the samples were placed in an oven at high temperatures over long periods of time to enable formation of nickel iron oxide alloy. The hematite nanowire arrays decorated with nickel particles and the iron nickel oxide nanowire samples were characterized for electrocatalysis and photocatalysis using cyclic voltammetry. The physical properties were tested using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX).