Photoelectrochemical Conversion of Toluene to Methylcyclohexane as an Organic Hydride by Cu₂ZnSnS₄-Based Photoelectrode Assemblies

Abstract

Direct photoelectrochemical conversion of toluene (TL) to methylcyclohexane (MC) with water has been examined as an organic hydride conversion using light irradiation. The production of MC from TL was observed on Pt/CdS/Cu(2)ZnSnS(4)/Mo photoelectrodes with anion-type ionomer membrane assemblies. A cathodic photocurrent was observed below 0.7 V vs RHE (V(RHE)) in 0.1 M Na(2)SO(4)/NaOH (pH 9.5) aqueous solution, and an apparent photocurrent density of 0.5 mA cm(-2) was obtained at 0 V(RHE) under the irradiation of a 300 W Xe lamp with a 420 nm cutoff filter. The yield of MC was measured by gas chromatography, and an 88% faradaic efficiency was estimated. This study suggests the possibility of direct energy conversion from solar energy to MC as an energy carrier of organic hydrides.

Sunlight‐Driven Production of Methylcyclohexane from Water and Toluene Using ZnSe : Cu(In,Ga)Se2‐Based Photocathode

“…Because the distributions of Ti (from TiO 2 ), Pt and P in this sample were all similar, it appears that the TiO 2 layer incorporated both the Pt and ionomer. In fact, the coexistence of the catalysts and ionomer is indispensable to the construction of a triple‐phase boundary for MCH production . After annealing, the Pt/TiO 2 layer became quite dense and its thickness was reduced to approximately 170 nm, as shown in Figures S6 and S7.…”

“…However, the efficient, selective and stable driving of the PEC reaction is still challenging due to various factors. These include an insufficient supply of the reactants (TL and water) to the reaction sites and/or the competitive hydrogen evolution reaction (HER) . The number of active sites on the photocathode surface in such devices is quite limited compared to conventional noble metal electrocatalysts loaded onto porous conductors .…”

“…[1][2][3][4] Although hydrogen is regarded as an attractive energy carrier, the low energy density of gaseous hydrogen and the resultant necessity of compression or liquefaction for practical storage and conveyance are important challenges. Previously, our group has reported the PEC hydrogenation of toluene (TL) using water as a hydrogen source [5][6][7][8] to synthesize a promising hydrogen carrier, methylcyclohexane (MCH). [9][10][11][12][13][14] This process is based on the reaction shown in Equation (1), and involves a significant Gibbs free energy increase.…”

Synthesis of Concentrated Methylcyclohexane as Hydrogen Carrier through Photoelectrochemical Conversion of Toluene and Water

“…We have previously proposed the direct PEC conversion of TL and water into MCH . Overall PEC conversion of TL to MCH with almost 100 % faradaic efficiency (FE) was achieved by using a combination of a cathode in the form of a membrane electrode assembly (MEA) and a photoanode .…”

CdS quantum dots sensitized solar cells made with as-synthesized Cu2ZnSnS4 counter electrodes

“…Doping with Se, the bandgap of CZTS might be tuned in a wide range of 1.0~1.5 eV continuously [4]. CZTS related structure has also attracted much attention in other fields such as photocatalysis, dye-sensitized solar cells (DSSC) or even quantum dots sensitized solar cells (QDSC) [5,6]. As a counter electrode, CZTS thin films exhibit low cost, chemical steadiness and excellent electro-catalytic activity as compared to Pt-coated ones.…”