Boosting catalytic performance of hierarchical Co/Co0.85Se microspheres via Mott-Schottky effect toward triiodide reduction and alkaline hydrogen evolution

Abstract

Interface engineered composites composing of metal and transition metal selenides have been deemed as promising substitutes as noble Pt in the fields of the energy conversion. Herein, the well-defined hierarchical Co/Co 0.85 Se microsphere with Mott-Schottky (M-S) effect was synthesized by the facile solvothermal method (Co/Co 0.85 Se-3). Interestingly, the as-obtained 3D Co 0.85 Se microsphere was assembled by 2D porous nanosheets. The characteristics including M-S heterojunction and hierarchical structure endows Co/Co 0.85 Se microsphere with high specific surface area, good conductivity, and synergistic effect between metal Co and Co 0.85 Se. More concretely, the optimized Co/Co 0.85 Se exhibits outstanding catalytic activity toward triiodide reduction reaction (IRR). When employed as the counter electrode (CE) catalyst for dye-sensitized solar cell (DSSC), a photoelectric conversion efficiency (PCE) of 8.31 % is achieved, which is 3.36 % higher than that of Pt-control device (8.04 %). Moreover, Co/Co 0.85 Se-3 displays remarkable catalytic activity for hydrogen evolution reaction (HER) with a low overpotential of 107 mV at the current density of 10 mA cm −2 under alkaline condition (1.0 M KOH), accompanying with Tafel slope of 140 mV dec −1 . Our discovery provides an effective approach to develop the cost-effective advanced catalysts to promote the application of DSSC and HER. The hierarchical Co/Co 0.85 Se microspheres with unique Mott-Schottky structure exhibited excellent catalytic performance in the fields of DSSC and HER. • Hierarchical Co/Co 0.85 Se microsphere with M-S effect was synthesized. • Synergy between Co and Co 0.85 Se increases the catalytic activity of Co/Co 0.85 Se-3. • Performance of Co/Co 0.85 Se-3 for DSSC was higher than that of Pt. • Co/Co 0.85 Se-3 exhibited remarkable catalytic property for alkaline HERs.