Molybdenum-Single Atom Catalyst for High-Efficiency Cobalt(III)/(II)-Mediated Hybrid Photovoltaics

Abstract

The exploration of catalysts with remarkable activity and good stability toward the Co2+/3+(bpy)3 redox reaction is highly desirable for hybrid photovoltaics. In this study, Mo-single-atom catalysts have been successfully synthesized through a facile “embedding–sintering–etching” approach. The as-obtained Mo- single-atom catalysts (SACs) featured the coordination of each Mo-single atom with four nitrogen atoms (Mo1–N4) within the nitrogen-doped carbon (N–C) support, which was verified by X-ray absorption fine structure analysis and high-angle annular dark-field scanning transmission electron microscopy. The electrocatalytic performance of the Mo–N–C SACs outperformed the activity of the reference N–C and Pt counterpart toward the Co2+/3+(bpy)3 redox reaction. Moreover, compared with the Pt counterpart, the Mo–N–C SACs presented good stability toward the Co2+/3+(bpy)3 redox reaction during the durability test. The power conversion efficiency of hybrid photovoltaics employing the Mo–N–C SAC-based cathode was up to 10.71%, which could be comparable to the device with the Pt counterpart (10.43%), exceeding that with reference N–C (7.17%). The Kelvin probe force microscopy measurement revealed that a moderate energy-level matching with the Co2+/3+(bpy)3 redox couple was achieved after the formation of Mo1–N4 moieties within the N–C support, which contributed to the enhanced catalytic activity. The superior catalytic activity correlated with favorable adsorption of Co2+/3+(bpy)3 redox and electron transferring from Mo1–N4 moieties to Co2+/3+(bpy)3 redox, which was confirmed by density functional theory calculations.

Enhancement of the triiodide reduction reaction by doping molybdenum in NiSe hierarchical microspheres: a theoretical and experimental study

“…[6][7][8][9][10] The power conversion efficiency (PCE) of DSSCs can be maximized by optimizing the dye-sensitized TiO 2 photoanode, electrolyte containing a redox couple (such as I 3 − /I − , Co 2+ / 3+ (bpy) 3 ), and counter electrode (CE). [11][12][13][14][15] From the perspective of redu-cing cost and achieving a satisfactory PCE, developing costeffective CE catalysts is indispensable as the main function of the CE is to collect electrons from the external circuit and then catalyse I 3 − to I − . [16][17][18] Although enormous efforts have been made to improve the activity of catalysts for future large-scale application, appropriate materials with excellent catalytic activity, fast charge-transfer capability, and satisfactory electrochemical stability are still needed for design by a mature and reliable strategy.…”

Fe Single Atom Catalysts Promoting Polysulfide Redox Reduction in Quantum Dot Photovoltaics

“…Compared with traditional catalysts, single-atom catalysts (SACs) have exhibited the huge potential advantages of catalytic properties toward various reactions stemming from the unique metal coordination environment and special electronic structure. − The atomically dispersed characteristics of SACs always involve the strong interactions between central metal atoms and coordination species on the support. − Their inherently atomic configurations originating from metal–support interactions strongly influence the catalytic behaviors toward various types of reactions . Previous studies have demonstrated that the enhanced catalytic performance could be ascribed to the strong interactions and considerable charge transfer between the central metal atoms and coordination species. − The representative merits of SACs are distinguished from that of traditional nanocatalysts. Enlightened by the above-mentioned findings, SACs could be explored finely as ideal catalysts for SRR in QD photovoltaics.…”

Experimental and Theoretical Exploration of In Situ Grown Fe3S4/Co3S4 Heterostructure as Efficient Catalyst for I3 − Reduction Reaction

“…[11][12][13] However, Platinum reserves are limited and expensive, severely inhibiting large-scale commercial applications. [14][15][16][17][18] Therefore, it is important to explore a simple yet controllable method to alternative Pt CE for DSSCs.…”