Bio-based carbon-enhanced tungsten-based bimetal oxides as counter electrodes for dye-sensitized solar cells

Tungsten-based bimetal oxides are first used as counter electrode catalysts for dye-sensitized solar cells. In this work, we introduce porous bio-based carbon into tungsten-based bimetal oxide by hydrothermal and annealing methods to improve the electrocatalytic properties of tungsten-based bimetal oxides. A structure transformation from nanorod to nanoflower is observed in cobalt tungsten oxide when porous bio-based carbon is used as the structure-directing agent. Bio-based carbon, which has a porous three-dimensional network structure, serves as an electrocatalytic support material in the tungsten-based bimetal oxide/bio-based carbon composites, reducing the agglomeration and grain size of tungsten-based bimetal oxides and providing rapid electron transfer paths. Tungsten-based bimetal oxide/bio-based carbon composite counter electrodes exhibit enhanced electrocatalytic activity and reduced charge-transfer resistance because of the synergistic effects of catalytic tungsten-based bimetal oxides and conductive bio-based carbon. The dye-sensitized solar cell with nickel tungsten oxide/biobased carbon counter electrode shows a high power conversion efficiency of 7.08%, surpassing that of dyesensitized solar cell with Pt counter electrode (6.46%). This work presents a general strategy for designing and fabricating porous bio-based carbon support inorganic compound materials for energy conversion devices.