Study On Synthesis And Properties Of N-TiO₂/Carbon Composites As Counter Electrode For Dye-Sensitized Solar Cells

Dye-sensitized solar cell (DSSC) has attracted much attention from the entire world due to its simple production procedure, environmental friendliness, high power conversion efficiency, and relatively low cost. Typically, a DSSC comprises three components, a photoanode, a counter electrode (CE), and an electrolyte. Pt is generally used as the CE catalytic material. However, Pt is an expensive noble metal with limited reserves and its electrochemical stability in corrosive electrolyte is also unsatisfactory. These greatly impede the large-scale application in DSSC at the commercial level, so finding inexpensive substitutes for Pt as a CE in the DSSC system is extremely urgent. Many materials have been studied by researchers in hopes of finding promising alternatives to Pt.Recently, many kinds of carbon materials such as carbon black, fullerene, carbon nanotubes (CNTs) and graphene, have been used as CEs for DSSC. However, carbon nanomaterials may have an excellent electrocatalytic activity and poor electrical conductivities at the same time. So it’s important to balance its electrocatalytic activity towards I3- reduction and electrical conductivity. Herein, we introduce the N-TiO2 (TiN-TiO2) into carbon nanomaterials with excellent electrical conductivity improve the electrocatalytic activity of carbon materials. N-TiO2/CNTs and N-TiO2/Graphene materials have been successfully synthesized and their performance as CE has been intensively investigated. The main contents and methods are shown as follow:Herein, CNTs supported N-TiO2 nano wires were synthesized by two steps hydrolysis of a titanium salt on CNTs and subsequent nitridation. In the composites CNTs interconnect with N-TiO2 nanowires each other, thus leading to a network structure that is favorable for contact between electrode and electrolytes. Benefiting from the electrocatalytic activity N-TiO2 and conductivity of CNTs, the N-TiO2/CNTs composites demonstrate a high power conversion efficiency of 7.16%, being comparable to that of noble Pt electrode.Here, we develop a simple & efficient strategy to configuring the N-TiO2/Graphene hybrids by assembling N-TiO2 on the conductive graphene. The filler-like N-TiO2 can successfully coat and assemble on the graphene surface, and lead to a rough and uneven structure. These unique characteristics are helpful for the intimate contact between electrode and electrolytes as well as mass transport and diffusion of electrolyte ions during electrochemical process. Benefiting from this, the as-made N-TiO2/Graphene hybrids deliver a PCE (rj) as high as 8.65%, being higher than that of Pt reference (7.55%) under the same conditons.