N-doped lotus seedpods biocarbon hybridized with NiCo2S4 as counter electrodes for dye sensitized solar cells

A facile and green approach to composites containing nitrogen doped lotus seedpods biocarbon (NALC) and NiCo2S4 (NCS) is reported. The composites present excellent electrocatalytic activity for reduction from I3− to I− due to the synergistic effect between the nanocrystalline NCS and the NALC. Dye-sensitized solar cells (DSSCs) assembled with the as-prepared NALC@NCS counter electrodes (CEs) achieve impressive photovoltaic conversion efficiency (PCE) of 8.58%, which is higher than that by the same structured cell with Pt (7.85%) and NCS (7.53%) CEs. Compared with other NCS based CEs, the NALC@NCS CEs show good durability and stability, suggesting that combining nanocrystalline catalyst with biocarbon is beneficial to stimulate the synergistic effect, and is a feasible strategy to optimal CEs for high performance DSSCs. Low cost NALC@NCS composites developed in this work are environmentally friendly, stable and efficient, which are believed to be good candidates for Pt-free CE materials in DSSCs and electrocatalysis applications.