Catalysts are widely used as high added value consuming goods in the modern industrial society, in particular, in the refinery and manufacturing industries. And catalysts are used in various areas ranging from large facilities for manufacturing hydrogen and for hydrodesulfurization, including plant-scale packed column reactors, to small devices such as hydrogen fuel cells. Particularly, fuel cells are considered to replace traditional fossil fuels based on petroleum and they are hailed as a new environmentally friendly energy source with a high market potential.
In hydrogen-fuel-cell systems, electricity is generated through a chemical reaction where hydrogen is oxidized in the negative electrode, and oxygen is reduced in the positive electrode to produce water. During the process, hydrogen fuel cells operate at relatively low temperatures of 50° C. to 100° C. and have a good point of having high energy density. However, they have a low power output due to their low reaction temperatures. Additionally, hydrogen fuel cells consume a large amount of platinum catalysts and water vapor needs to be removed from the surfaces of hydrogen fuel cells. Particularly, tens of thousands of oxidation and reduction that take place during electricity generation lower catalytic activities thereby pulling down performance of fuel cells.
Equal sizes and purity of catalysts are not influential factors in plant-scale facilities of the traditional industries but are highlighted as key factors, in fuel-cells whose reactions happen in a limited space and consume a large amount of platinum.
In Korean Patent Publication No. 2009-0045412, a catalyst particle is presented. The catalyst particle is configured to comprise M core/M shell structures, whose inner particle core is palladium and whose outer particle shell is platinum, to solve the above described problem. However, it has the disadvantage that catalytic activities are reduced due to colloidal dispersion liquids which are not removed. And in Korean Patent Publication No. 2006-0082595, a method for manufacturing an electrode catalyst for fuel cells is presented. The method comprises manufacturing a precursor solution by dissolving metallic compound particles consisting of palladium and precursor compounds consisting of activated particles with a core-shell structure having platinum coated layers or alloy-containing-platinum coated layers on the entire surface of the metallic compound particles thereby having palladium, and drying up metallic compound particles put in a catalytic carrier. However, it has the disadvantage that catalyst particles do not have equal sizes.