N-Doped Hierarchical Hollow Mesoporous Carbon as Metal-Free Cathode for Dye-Sensitized Solar Cells

Abstract

In this study, novel nitrogen (N)-doped hollow core-mesoporous shell carbon (N-HCMSC) capsules with high surface area are synthesized by simple three-step processes and explored as metal-free counter electrode (CE) in comparison with undoped HCMSC in dye-sensitized solar cells (DSSCs). It is shown that N-HCMSC significantly improves the catalytic activity toward the reduction of both Co­(bpy)3 3+ and I3 – due to much lower charge-transfer resistance (R CT) at the CE/electrolyte interface. This is attributed not only to excellent surface properties including three-dimensionally interconnected hierarchical marco/mesoporosity with high surface area but also to N doping in N-HCMSC framework. Among various N species in the N-HCMSC framework, pyridinic and quaternary N species are considered to contribute significantly to the catalytic activity. In addition, N-HCMSC CE exhibits much better electrochemical stability than Pt CE toward both Co­(bpy)3 2+/3+ and I–/I3 – redox reactions. The N-HCMSC enhances the cell efficiency and fill factor up to 8.76 and 77.6%, respectively, at one sun illumination and is readily applicable as a potential alternative of costly Pt-based CE for DSSCs with Y123-sensitized photoanodes.

Facile fabrication of low‐cost low‐temperature carbon‐based counter electrode with an outstanding fill factor of 73% for dye‐sensitized solar cells

“…We emphasize that the remarkably high value of FF of the device based on H-CE (0.73) is one of the highest values reported in the literature especially for the metal-free carbon CE-based liquid DSSCs ( Figure 5). 45,[53][54][55][56][57][58][59][60][61][62][63][64][65]…”

Heteroatom tri-doped porous carbon derived from waste biomass as Pt-free counter electrode in dye-sensitized solar cells

“…[10][11][12][13][14][15][16] Thus, alternatives to the Pt CE have been extensively explored, such as transition metal compounds, 14,17,18 conducting polymers 19,20 and carbon-based materials. [21][22][23][24][25][26][27][28] Among these materials, the carbon-based materials, including mesoporous carbon, 22,27 hollow carbon nanospheres, 23 graphene [24][25][26] and activated carbon, 28 are the most popular electrode materials owing to their intrinsic chemical inertness against corrosive electrolyte as well as high surface areas. Further investigations reveal that the edges and defect sites within the graphitic carbon framework provide active sites for efficient triiodide reduction.…”

Nitrogen Doped Microporous Carbons with Tunable and Selective performances in Supercapacitor and Heterogeneous Catalysis

“…In term of heteroatoms doped carbons, some nonmetallic elementals including N, B, S and P [9][10][11][12], can be employed as dopants to modulate the surface feature, energy band structure to improve the application performances. As an intimate neighbor of C in periodic label, N is the most feasible dopant for the conjugation of its lone-pair electrons with the delocalized system of graphitic carbon network with minimal lattice distortion as a sequence of the rich electrons feature of N and the similar atomic radius to C. As for N doped carbons (NCs), the N forms play vital roles on the electronic structure and surface properties of C-N framework, for instance, pyridinic-and pyrrolic-typed N located at the rim of the C-N network facilitate higher capacitive performance via pseudocapacitance contribution owing to the susceptibility to oxidation [13,14]; whereas the graphitic N by replacing skeletal C is beneficial for a higher conductivity owing to the electron donating nature [15]; additionally, the increased surface polarity because of the electronegativity difference between N and C enhances the hydrophilicity [16,17], which is also vital for higher capacitive performance. On the other hand, the electron donor feature of pyridinicand pyrrolic N can function as active center promoting the catalytic activity toward certain redox reactions [18,19], graphitic-N further boost the catalytic activity by reducing the work function of C-N framework besides the conductivity contribution 5 [20].…”