Facile charge transfer in fibrous PdPt bimetallic nanocube counter electrodes

Abstract

The nature of the physicochemical processes and the surface reactivity of a counter electrode (CE) are determined by its surface atomic composition and area. In this paper, we investigated the role of Pd atom concentration in the electrocatalytic properties of poriferous bimetallic PdPt nanostructured CEs in dye-sensitized solar cell (DSSC) devices. It was found that the physicochemical properties and surface reactivity, which are reflected by the charge transfer resistance and electrocatalytic properties, increased with increasing Pd atom concentration and were optimum at a concentration of 2.5 mM. The DSSC device fabricated using the optimum bimetallic PdPt nanostructures produced short circuit current (J_sc), open circuit voltage (V_oc) and fill factor (FF) values as high as 9.52 mA cm⁻², 0.63 V and 0.37 respectively, which correspond to a power conversion efficiency (PCE) value of up to 2.22%. This is two-fold higher than the PCE of a device utilizing a pristine Pt CE (1.11%). The performance enhancement is attributed to the unique surface physicochemical properties of the prepared CE due to the poriferous structure with its large surface area and bimetallization. The synthesis and device characterization are discussed in detail.