Preparation of Hydrophilic Carbon Nano-Particles and Its Application to the Counter Electrodes of DSSCs
Authors: Ikeda Shoichiro , Nobumoto Akinari , ONO Hideo , ONO Shinji , Kouhnavard Mojgan , Ludin Norasikin Ahmad , Sopian Kamaruzzaman , Miyake Mikio 
Published: February 2020

Hydrophilic carbon nano-particles have been prepared from a synthesized graphite block using electro-oxidation method in pure water. They are sub-micro meter in diameter depending on the electrolysis condition. They are used as the activator of lead-acid batteries and solid lubricants in non-oily lubricants as already reported at PRiME2012. In this presentation, we will introduce the application to the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs) instead of Pt. We will report the preparation method, the results in characterization, and applications of hydrophilic carbon nano-particles especially on CEs in DSSCs. The weight % of solid carbonous material is 0.4 by the conventional electrolysis method around 10 V DC for 45 days. Increasing in the ratio of the graphite to the cell volume, the electrolysis time decreased and the weight % becomes 0.6 within 3 weeks. By XRD analysis, the dried powder of the produced material consists of mellitic acid (benzenehexacarboxylic acid) and graphite. CE was prepared by doctor blading a mixture of hydrophilic carbon (HC) nano-particles with TiO2 colloids on a FTO glass substrate. Thereafter, HC-CE was characterized using X-ray diffraction, profilometry, four-point probe testing, and CV. A 2 𝜇m thick HC-CE revealed a comparable catalytic activity to that of the Pt electrode under the same experimental conditions. A DSSC based on HC-CE was analyzed and showed 𝐽sc of 6.87 mA/cm2 close to that of DSSC with Pt-CE (7.0 mA/cm2). More importantly, DSSC based on HC-CE yielded a power-conversion efficiency (𝜂) of 2.93% under AM 1.5 irradiation (100 mW/cm2), which was comparable to that of DSSC based on conventional Pt-CE.Hydrophilic carbon nano-particles have been prepared from a synthesized graphite block using electro-oxidation method in pure water. They are sub-micro meter in diameter depending on the electrolysis condition. They are used as the activator of lead-acid batteries and solid lubricants in non-oily lubricants as already reported at PRiME2012. In this presentation, we will introduce the application to the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs) instead of Pt. We will report the preparation method, the results in characterization, and applications of hydrophilic carbon nano-particles especially on CEs in DSSCs. The weight % of solid carbonous material is 0.4 by the conventional electrolysis method around 10 V DC for 45 days. Increasing in the ratio of the graphite to the cell volume, the electrolysis time decreased and the weight % becomes 0.6 within 3 weeks. By XRD analysis, the dried powder of the produced material consists of mellitic acid (benzenehexacarboxylic acid) and graphite. CE was prepared by doctor blading a hydrophilic carbon (HC) nano-particle on a FTO glass substrate. Thereafter, HC-CE was characterized using X-ray diffraction, profilometry, four-point probe testing, and CV. A 2 𝜇m thick HC-CE revealed a comparable catalytic activity to that of the Pt electrode under the same experimental conditions. A DSSC based on HC-CE was analyzed and showed 𝐽sc of 6.87 mA/cm2 close to that of DSSC with Pt-CE (7.0 mA/cm2). More importantly, DSSC based on HC-CE yielded a power-conversion efficiency (𝜂) of 2.93% under AM 1.5 irradiation (100 mW/cm2), which was comparable to that of DSSC based on conventional Pt-CE.