Hydrogen has always been a promising alternative to fossil fuels. It could be generated from water using clean electricity produced by solar and wind. The generation, water splitting, takes place in the flow cell electrolyzer. The main cost of this method is from the noble metal electrode. Platinum (Pt) is an ideal material for water splitting. However, the low abundance, high prices and poor durability restrict its industrial applications in water splitting.

There are two approaches to overcome the shortcomings of Pt. One is to find a low-cost alternative, including transition-bimetal, metal oxide and metal sulfide with 2D/3D structures. The other way is to enhance the specific surface area of Pt with low loading. In this thesis, we present 1) a stable bi-metallic cathode, whic...[ Read more ]

Hydrogen has always been a promising alternative to fossil fuels. It could be generated from water using clean electricity produced by solar and wind. The generation, water splitting, takes place in the flow cell electrolyzer. The main cost of this method is from the noble metal electrode. Platinum (Pt) is an ideal material for water splitting. However, the low abundance, high prices and poor durability restrict its industrial applications in water splitting.

There are two approaches to overcome the shortcomings of Pt. One is to find a low-cost alternative, including transition-bimetal, metal oxide and metal sulfide with 2D/3D structures. The other way is to enhance the specific surface area of Pt with low loading. In this thesis, we present 1) a stable bi-metallic cathode, which has good hydrogen evolution reaction (HER) activity in all pH range; 2) the use of adsorbed quinone to produce a high specific area Pt on commercial carbon substrate for HER and electro-organic synthesis.

Firstly, guided by a simplified first principle calculation that indicates enhanced catalytic activity from a cobalt copper (CoCu) bi-metallic electrode, we synthesis electrodeposited CoCu bi-metallic electrodes with various morphologies. These bi-metallic electrodes show high HER catalytic activity and good durability in both acid and alkaline conditions.

Secondly, we develop a method of catalyst deposition on carbon in analogy to the underpotential deposition (UPD) mediated deposition. Instead of metal atoms, the surface-confined mediators we resort to are quinone adsorbates. Quinone derivatives adsorb strongly through dispersive interactions and can provide a sufficiently low potential to reduce metal cations. In this thesis, we employ five quinone derivatives for the deposition of silver and platinum on carbon black and carbon paper. We prove that the method can lead to a controllable deposition of ultra-low Pt loading nanostructures with high catalytic activities in HER.

Other than water electrolysis, quinone adsorbate-mediated deposition Pt-nanoparticles on commercial carbon paper could also serve in electro-organic synthesis. This work is the first to illustrate its application in halide salt catalyze indole electro-oxidative rearrangement. Different from conventional graphite rod or Pt plate, by using Pt decorated carbon paper as the anode, we can have a stable 80 - 90% yield. Meanwhile, the excellent stability of the electrode indicated its potential in the industry.