How Dimensionally Stable Anode(DSA) is Used in Hydrogen Production?

How Dimensionally Stable Anode(DSA) is Used in Hydrogen Production?

Carbon emission from carbon-based fuels causes environmental problems, while hydrogen is regarded as a new energy source to replace fossil fuels. The production and storage of hydrogen have become essential technologies recently. Electrolysis of water using electricity or sunlight is the method that is being used for the environmentally benign production of hydrogen. However, hydrogen production through electrolysis is hindered by the slow oxygen evolution reaction (OER) at the anode kinetically. The hydrogen evolution reaction (HER) at the cathode is a two-electron reaction; however, the OER at the anode is a four-electron reaction with several steps, requiring higher energy to overcome the kinetic barrier.

Therefore, it is important to develop an OER catalyst for electrolysis with high efficiency. Dimensionally stable anodes(DSA) adopting ruthenium (Ru) oxide and iridium (Ir) oxide were considered highly efficient as OER catalysts for hydrogen production. However, these catalysts have some drawbacks, such as high cost owing to platinum-group metal (PGM) and low stability in acidic and basic media. Thus, there arises a great need for the OER catalyst that contains low metal loading and also exhibits moderate catalytic activity and stability.
 
Traditionally, the dimensionally stable anode(DSA) is made by thermal decomposition. However, the dimensionally stable anode made by thermal decomposition always has some defects such as composition segregation and coarse particles, which are difficult to control. What is more, it is difficult to make a precise composition coating and high heat is required. Therefore, in order to overcome these disadvantages, Scientists researched dimensionally stable anodes which were fabricated by the electrodeposition (ED)method. ED, the fabrication method that applies current or voltage to deposit metal onto a substrate by reducing the metal ions in the ED solution, has been used to prepare a uniform film on a mesh substrate.

The DSA has been prepared using the ED method prepared Ti/TiO2/Ir electrode as DSA electrode with iridium precursor solution. Also, scientists synthesized the lead dioxide(PbO2) layer on Ti/TiO2 substrate using a lead precursor solution. These studies have reported that the DSA anodes prepared with the ED method comprise one kind of metal or metal oxide. The DSA anodes with different Ru to Ir ratios were fabricated by co-electrodeposition, which is easy to control the element ratio in the DSA anode. The mesh-type DSAs; RuO2/Ti and (RuO2-IrO2)/Ti electrodes were prepared as oxygen evolution electrodes in an acidic and alkaline medium. The ED conditions, such as the applied current density and total cycle numbers, were optimized to obtain the RuO2/Ti electrode with high film uniformity.