High-surface-area nanomesh graphene with enriched edge sites as efficient metal-free cathodes for dye-sensitized solar cells

Abstract

Exploiting cost-effective and highly efficient counter electrodes (CEs) has been a persistent objective for practical application of dye-sensitized solar cells (DSSCs). Here, we present an efficient CE by using pure three-dimensional (3D) nanomesh graphene frameworks (NGFs) which are synthesized via a template-directed chemical vapor deposition (CVD) approach. The high-surface-area 3D NGFs associated with the enriched surface edge defects make it very efficient towards I3(-) reduction even without any Pt catalyst. More interestingly, by virtue of the interpenetrating graphene frameworks, the NGFs exhibit excellent electron conductivity, thus leading to facile charge transfer. Consequently, the DSSCs with pure NGFs as CEs display a power conversion efficiency of 7.32%, which is comparable to that of Pt as CEs (7.28%), thereby exhibiting great potential as low-cost and highly efficient CE materials for large-scale deployment of DSSCs.

Three-dimensional graphene networks and RGO-based counter electrode for DSSCs

“…In order to avoid the negative inuence from the discontinuous structure of the graphene basal plane in the RGO, Jang's group fabricated a CE based on a p-doped three-dimensional graphene nanonetwork (3DRGO), and the resulting electrocatalytic activity was reported to be comparable to that of a Pt electrode. 14 Recently, our group employed three-dimensional graphene networks with low defect density levels and a natural continuous structure (3DGNs, prepared by using the chemical vapor deposition (CVD) method to provide a network amenable to fast transport of electrons) to prepare the CE, and the obtained high performance conrmed the above-mentioned point of view, 15 which is in line with the report from Yang et al 16 However, the obtained photovoltaic performance was still far poorer than that predicted. The electrocatalytic activity of graphene towards the I 3 À /I redox reaction is well known to be determined by the number of available sites, which arise from the defects of the graphene basal plane.…”

Enhanced electrocatalytic performance of nickel diselenide grown on graphene toward the reduction of triiodide redox couples

“…In detail, the E pp value is negatively correlated with the standard electrochemical rate constant and positively with overpotential loss, and J Red-1 is positively correlated with reaction velocity and electrocatalytic activity. 10,42 The NiSe 2 /RGO NPs CE exhibited a lower E pp value (232 mV) and a higher J Red-1 value (2.80 mA cm À2 ) than those of the NiSe 2 NPs CE (E pp ¼ 499 mV, J Red-1 ¼ 1.56 mA cm À2 ), revealing the better intrinsic electrocatalytic activity of the NiSe 2 /RGO NPs CE as well as a synergistic catalytic effect between NiSe 2 and graphene. In comparison with the Pt (E pp ¼ 261 mV, J Red-1 ¼ 2.22 mA cm À2 ) CE, the E pp and J Red-1 of NiSe 2 /RGO NPs CE are also better, signifying that the electrocatalytic activity of the NiSe 2 / RGO NPs CE is even superior to that of the Pt CE.…”

Recent Progress of Graphene-Based Photoelectrode Materials for Dye-Sensitized Solar Cells

“…Graphene could also be used as a current collector. Yang et al incorporated 2D graphene into the TiO 2 nanostructure, aiming at increasing light collection, preventing charge recombination, and thus enhancing the charge transportation rate [154]. Bavir and Fattah employed a composite of TiO 2 and graphene as photoelectrode to replace the TiO 2 -ZnO composite [18].…”