Molybdenum disulfide/reduced graphene oxide hybrids with enhanced electrocatalytic activity: An efficient counter electrode for dye-sensitized solar cells

Synergistic effect of interface and defect engineering of MoC/MoO2 nano dot encapsulated N-doped carbon nanoflowers for highly durable dye-sensitized solar cells

The design and fabrication of advanced counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) are limited by the scarcity of active sites and poor durability. Herein, we report the controlled preparation of a heterostructured nanoreactor CE based on defect-rich N-doped carbon nanoflowers (NCF) encapsulating MoC/MoO2 nano dots (NDs) in a well-defined heterophase (MoC/MoO2-NCF). The MoC/MoO2 NDs were uniformly dispersed on the NCF, and the NCF limited the size of the MoC/MoO2 NDs and prevented their agglomeration, thus maximizing the electrochemically active surface area of MoC/MoO2. Moreover, the synergistic effect between the MoC/MoO2 interface and the N-defects is conducive to the full exposure of the active sites. Furthermore, theoretical calculations revealed that the MoC/MoO2 heterojunction played a unique role in modulating the electronic structure and regulating the adsorption energy of tri-iodide in the iodide reduction reaction. The MoC/MoO2-NCF CEs in DSSCs demonstrated a power conversion efficiency (PCE) of 9.92% and high durability, exceeding the PCE (8.36%) and durability of Pt CEs. Overall, this study offers insights into the controlled synthesis of high-performance Mo-based composite CE materials for DSSCs.

Synthesis of Single Crystal 2D Cu2FeSnS4 Nanosheets with High-Energy Facets (111) as a Pt-Free Counter Electrode for Dye-Sensitized Solar Cells

Two-dimensional Cu₂FeSnS₄ (CFTS) nanosheets with exposed high-energy facets (111) have been synthesized by a facile, scalable, and cost-effective one-pot heating process. The CFTS phase formation is confirmed by both X-ray diffraction and Raman spectroscopy. The formation mechanism of exposed high-energy facet CFTS growth is proposed and its electrochemical and photoelectrochemical properties are investigated in detail to reveal the origin of the anisotropic effect of the high-energy facets. Dye-sensitized solar cells (DSSC) achieve a favorable power conversion efficiency of 5.92% when employing CFTS thin film as a counter electrode, suggesting its potential as a cost-effective substitute for Pt in DSSCs.

Applications of Ceramic/Graphene Composites and Hybrids

Research activity on ceramic/graphene composites and hybrids has increased dramatically in the last decade. In this review, we provide an overview of recent contributions involving ceramics, graphene, and graphene-related materials (GRM, i.e., graphene oxide, reduced graphene oxide, and graphene nanoplatelets) with a primary focus on applications. We have adopted a broad scope of the term ceramics, therefore including some applications of GRM with certain metal oxides and cement-based matrices in the review. Applications of ceramic/graphene hybrids and composites cover many different areas, in particular, energy production and storage (batteries, supercapacitors, solar and fuel cells), energy harvesting, sensors and biosensors, electromagnetic interference shielding, biomaterials, thermal management (heat dissipation and heat conduction functions), engineering components, catalysts, etc. A section on ceramic/GRM composites processed by additive manufacturing methods is included due to their industrial potential and waste reduction capability. All these applications of ceramic/graphene composites and hybrids are listed and mentioned in the present review, ending with the authors' outlook of those that seem most promising, based on the research efforts carried out in this field.

Recent progress on nanostructured carbon-based counter/back electrodes for high-performance dye-sensitized and perovskite solar cells

Dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) favor minimal environmental impact and low processing costs, factors that have prompted intensive research and development. In both cases, rare, expensive, and less stable metals (Pt and Au) are used as counter/back electrodes; this design increases the overall fabrication cost of commercial DSSC and PSC devices. Therefore, significant attempts have been made to identify possible substitutes. Carbon-based materials seem to be a favorable candidate for DSSCs and PSCs due to their excellent catalytic ability, easy scalability, low cost, and long-term stability. However, different carbon materials, including carbon black, graphene, and carbon nanotubes, among others, have distinct properties, which have a significant role in device efficiency. Herein, we summarize the recent advancement of carbon-based materials and review their synthetic approaches, structure-function relationship, surface modification, heteroatoms/metal/metal oxide incorporation, fabrication process of counter/back electrodes, and their effects on photovoltaic efficiency, based on previous studies. Finally, we highlight the advantages, disadvantages, and design criteria of carbon materials and fabrication challenges that inspire researchers to find low cost, efficient and stable counter/back electrodes for DSSCs and PSCs.