May 21 2021 12:00 pm
Electrodeposition of NiMo Bimetallic Nanoporous Foam for Electrochemical Hydrogen Evolution
Dr. Falak Sher
Zoom Meetings (Online)
MS Thesis defense
The environmental issues and constant depletion of fossil fuel with continuously rising demand of energy consumption compels us to explore and develop clean alternate source of energy. Hydrogen is a green fuel with very high energy density. This which make the electrocatalytic water splitting an attractive research field as it is most efficient, clean and cost-effective method for the production of hydrogen gas. Water electrocatalysis involves the HER (hydrogen evolution reaction) at cathode and OER (oxygen evolution reaction) at anode. However, this splitting process is hampered due to sluggish kinetics of OER. Noble metals (e.g. Pt, Pd, Ru) are considered as the benchmark electrocatalysts for both HER and OER but they are expensive due to limited availability and thus commercially no viable for production of hydrogen. First row and second row transition metals and their bimetallic alloys are promising electrocatalyst effect with good catalytic properties. The aim of this research project was to synthesize bimetallic Nanoporous electrocatalyst that can facilitate the water electrocatalysis at low electrical potential. For this purpose, we prepared NiMo bimetallic alloys with varying chemical compositions. These alloys were deposited on Cu foil using electrodeposition method. The Dynamic Hydrogen Bubble Templating technique was employed in alkaline medium at -8V for 300s with ammonium Sulfate salt for the production of hydrogen bubbles on the electrode surface and thus the modification of microstructural properties of catalysts. Nanoporous NiMo bimetallic alloy were characterized using powder X-ray diffraction and Scanning electron microscopy. The electrochemical analysis of the NiMo bimetallic alloys with different chemical compositions was performed in alkaline medium of 1M (KOH) and result showed that NiMo.b (Ni:Mo= 15:1) has an overpotential of 20mV and Tafel slope of 266.16 mV/dec for HER with more than 14 h stability in alkaline medium in comparison to the pure metals and other NiMo bimetallic with other two ratios (10:1) and (20:1). The low overpotential and lower value of Tafel slop for this electrocatalysis show that it has superior electrocatalytic activity for HER. This research demonstrates the dynamic hydrogen bubbles templating technique is very promising for controlling the pore size and microstructure of Nanoporous bimetallic alloys and thus improving the electrocatalytic performance of these materials.