課題番号 ：S-20-SH-0016
利用形態 ：共同研究型支援
利用課題名（日本語） ：白金系触媒を用いたグルコン酸の電気化学酸化
Program Title (English) ：Investigation on electrochemical oxidation of gluconic acid using platinum
based catalyst
利用者名（日本語） ：倪慶清
Username (English) ： Qing-Qing Ni
所属名（日本語） ：信州大学　繊維学部
Affiliation (English) ：Faculty of textile,Shinshu University

１．概要（Summary ）
Glucose is considered as a promising biomass fuel and energy source for biofuel cell. In recent years, as replacement of instable enzymes, platinum based abiotic catalysts have received much attention for catalytic oxidation of glucose. However, catalytic product of glucose in room temperature is mostly gluconic acid and there are still much chemical energy which is not released from glucose. This research is to investigate the feasibility that the gluconic acid is further catalyzed under increasing temperature by using platinum based catalysts and also to study the oxidation behavior of gluconic acid and catalytic performance of platinum based catalyst.

２．実験（Experimental）
Platinum based inorganic catalyst was used to catalyze the glucose and gluconic acid due to its stability. In case of the effect of heterogeneous substance on electrochemical potential, platinum catalyst was directly electroplated onto commercial platinum sheet as electrode.
H-shape electrochemical cell, separated with ion exchange membrane, is used to evaluate the electrochemical response of glucose and gluconic acid at different temperature (20oC – 60oC). At the same time, oxidized products after constant current discharge are planned to be analyzed by organic spectral analysis.
At initial stage, the response behavior of glucose was evaluated in H-shape electrochemical cell by using electroplated Pt catalyst on Pt board connected with a Pt string, as illustrated below.

Scheme 1 Three-electrode measurement system. Setup: Each 20 ml H-shape Cell, Separator: Nafion membrane with 183 um thickness, Anode: Electroplated Pt on Pt board connected with a Pt string, Cathode: Electroplated Pt on Pt board connected with a Pt string, Anode electrolyte: 14 ml 0.1 M phosphate buffer (PB) solution, 0.5 M glucose, Cathode electrolyte: 14 ml 0.1 M PB solution, Temperature: about 20-25 oC.

３．結果と考察（Results and Discussion）
In case of the effect of heterogeneous substance on electrochemical potential, platinum catalyst was directly electroplated onto commercial platinum sheet as electrode. After electroplating, silvery platinum board turned black. The platinum electrodes were both used as anode and cathode.
Due to limited time, the open-circuit voltage and short-circuit current were firstly measured by using two-electrode system under the same measurement conditions without the addition of the reference electrode.
The voltage change between anode chamber and cathode was measured with increasing time. As can be seen in Figure 1, the initial voltage could reach close to 0.76 V.

Figure 1 The voltage change between anode chamber and cathode with increasing time. In this system, 0.5 M glucose in anode chamber was used as and electroplated Pt on Pt board connected was used as anode electrode. The electrolyte in anode and cathode chambers was 0.1 M PB solution.

Then, by using similar system, the current change between anode chamber and cathode were observed with increasing time. As seen from Figure 2, it can be easily found that the short-circuit current decreased due to the deceased voltage. When removing the O2 in anode chamber by filling N2, the decrease became slight. When continually filling O2 into cathode, obvious increase of the current was found. We have, thus, found that out cell with two Pt electrode works for oxidation glucose with filling O2. It can be used further for pursuing complete oxidation of glucose.

Figure 2 The short-circuit current change between anode chamber and cathode with increasing time under similar system to the abovementioned.

４．その他・特記事項（Others）
In this research, preparation of Pt electrode and electrical measurements were performed by Dr. Yan Yongjie as a support of nanotechnology platform.

５．論文・学会発表（Publication/Presentation）
なし

６．関連特許（Patent）
なし