Facile solvothermal synthesis of Pt-Cu nanocatalyst with improved electrocatalytic activity toward methanol oxidation

Muhammad Mehmood, Muhammad Tariq, Ayaz Hassan, Abdul Raziq, Abdur Rahim, Jehangeer Khan
2019 Journal of the Serbian Chemical Society  
A binary metal nanocatalyst of platinum and copper was synthesized using a facile solvothermal process (polyol method). The synthesized catalyst was characterized using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performance of the synthesized carbon supported binary metal catalyst, Pt-Cu/С, toward methanol oxidation reaction was checked and then compared with the commercial Pt/C (ETEK) catalyst, using
more » ... talyst, using cyclic voltammetry and chronoamperometric techniques. The Pt-Cu/C catalyst was found to be cubic in shape with indentations on the particle surface, having platinum to copper atomic composition of 4:1, i.e., (Pt 4 Cu). The peak current density for Pt-Cu/C catalyst recorded as 2.3 mA cm -2 at 0.7 V (vs Ag/AgCl) and 50 mV s -1 , was two times higher than the current density of the commercially available Pt/C catalyst (1.16 mA cm -2 at 0.76 V). Moreover, the Pt-Cu/C catalyst was found to be more durable than the commercial Pt/C catalyst, as the Pt-Cu/C retained 89 % of its initial current density, while the commercial Pt/C catalyst retained 65 % of its initial current density after 300 potential cycles. adverse environmental problems such as climate change, depletion of ozone layer, air and water pollution, production of toxic wastes, global warming, etc., which in turn, is affecting both humans and wild life. It is due to the fact that on combustion, fossil fuels produce gas compounds like SO x (SO 2 ⋅SO 3 ) and NO x (NO, NO 2 ), particulate matter which are also known as primary air pollutants and are eventually the reason for the formation of secondary air pollutants i.e., acid rain, smog, etc. 2 Nowadays, based on availability of energy resources, various energy technologies have been developed, for example, there is wind turbine technology to take advantage of wind energy and convert it to electric power which is then used for different purposes. Similarly, water turbines are used to convert hydraulic energy into electricity, solar photovoltaic panels to convert solar energy into electricity, nuclear reactors to generate nuclear energy for several applications. Moreover, batteries, supercapacitors, fuel cells etc. are other common types of energy technologies. Among these various technologies, fuel cells were extensively studied. 3-5 Unlike, batteries, fuel cells directly produce electricity from a fuel, which could either be hydrogen (H 2 ) or small organic molecules (CH 3 OH, C 2 H 5 OH, HCOH, etc.). Methanol, as a fuel, has immense potential among other hydrocarbons, due to; its higher electrochemical activity, simpler molecular structure, easy storage and handling as its liquid at room temperature, low production cost than hydrogen as methanol can easily be produced by fermentation of agricultural products and can also be obtained from fossil fuels and from biomasses. Moreover, it also has higher energy density than hydrogen. 6 A common example of methanol fuel cell is direct methanol fuel cells (DMFCs), in which methanol is directly used in liquid form. The main components of a direct methanol fuel cell include; electrodes (anode and cathode) and a proton conducting membrane. Generally, the anode in DMFCs is composed of platinum or platinum-based materials (Pt-Ru, Pt-Cu, etc.). 7 The basic problem with direct methanol fuel cells (DMFCs) was the adsorption of carbon monoxide and other intermediate species to the catalyst surface. The adsorption of these species slow oxidation process of methanol in direct methanol fuel cells. 8 To overcome this problem, several researcher have adopted the strategy of alloying the platinum with other metals like Ru, Pd, 9 Ir, 10 Pb, 11 Ni, 12 Co, 13 Au, 14 V, 15 Fe 16 and Cu 17-20 whereas, some has fabricated ternary platinum based catalysts for methanol oxidation. 21 It was reported that alloying other metals with platinum makes it more efficient for methanol oxidation reaction (MOR) by changing the electronic structure of platinum by "ligand effect", which may in turn loosen the strong adsorption affinity of carbon monoxide (CO) on platinum surface and hence less poisoning. 22 The present study, therefore, ________________________________________________________________________________________________________________________ Available on line at www.shd.org.rs/JSCS/ (CC) 2019 SCS.
doi:10.2298/jsc190131041m fatcat:2ttw55dvibakdav54msksjopai