Amperometric H2 sensor with PtxPdy alloy electrode prepared by pulsed electrodeposition method

Method of deposition of electrocatalysts plays a vital role in controlling the particle size and in turn decides the catalytic activity of electrocatalysts in various applications. The present study is on preparing the PtxPdy alloys on gas diffusion layer (GDL) by pulsed electrodeposition method. The prepared electrodes are used as sensing electrodes in amperometric H-2 sensor. This sensor operates in two electrode mode similar to proton exchange membrane fuel cell and uses Nafion as proton conducting electrolyte. Sensing electrodes with three different compositions of PtxPdy alloys were developed. Field emission scanning electron microscopy studies of PtxPdy alloys showed uniform distribution with spherical morphology. Energy dispersive X-ray mapping of alloy confirmed the uniform distribution of Pt and Pd in PtxPdy. The formation of alloy was proved by grazing incidence X-ray diffraction and high resolution transmission electron microscopy. Compositions of three different PtxPdy alloys were investigated by energy dispersive X-ray analysis and inductively coupled plasma mass spectrometry. Electrochemical active surface area of PtxPdy alloys was measured by carrying out cyclic voltammetry. Sensors with Pt(x)Pd(y )alloy based diffusion electrodes were assembled and tested. All PtxPdy alloys based sensors showed a linear variation with percentage concentrations of H-2 (1-5%). Sensor having diffusion electrode with PtxPdy alloy of composition Pt54Pd46 in two electrode mode gave better response behaviour for H-2 in Ar compared to pristine Pt.