Efficient NiO Impregnated Walnut Shell-Derived Carbon for Dye-Sensitized Solar Cells

The conversion of biowaste into useful materials for technological uses has received a lot of interest in recent years. Here, a NiO@walnut shell (WS)-derived carbon composite (NiO@WS-derived carbon) was synthesized to be employed as an alternate counter electrode (CE) in dye-sensitized solar cells (DSSCs). The morphological studies demonstrated that NiO nanoparticles were uniformly impregnated into the WS-derived carbon frameworks. The electrochemical investigations showed that the NiO@WS-derived carbon composite CE displayed high catalytic activity and significant stability toward the I3–/I– redox couple after 100 CV cycles. The charge-transfer resistance of the NiO@WS-derived carbon composite CE (2.21 Ω) was also lower than that of the Pt-CE (3.04 Ω). The power conversion efficiency of the assembled DSSC with NiO@WS-derived carbon composite CE is 8.30%, which is comparable to Pt-CE (8.18%). NiO@WS-derived carbon composite CE is a possible alternative to the pricey Pt-CE in DSSC due to its low cost and excellent catalytic activity with acceptable stability.