Preparation of Sb-Doped SnO2 Nanoparticle with High Surface Area for Use As a Stable Anode Catalyst Support for PEM Electrolyzers.

Abstract

Proton exchange membrane (PEM) water electrolysis has been considered as one of the most promising technologies for large H2 production. While the cost and stability of PEM are the main obstacles for the commercial application. Here we report a cost-effective catalyst, which consists of IrO2 nanoparticles supported on Sb-doped SnO2 (ATO). ATO support is synthesized by using templating process and hydrothermal method to improve its thermal stability. It has a mesoporous structure, small particle size, and high surface area. After loading IrO2 via Adams fusion method, the IrO2/ATO catalyst shows high electrochemical stability, according to repetitive potential cycling. This catalyst also shows a good electrochemical performance in single cell. Firstly, we prepared a series of ATO samples and named them as the Brunauer Emmett Teller model (BET) surface area. The surface area and pore size distribution of the obtained ATO samples were calculated by BET and nonlocal density functional theory (NLDFT). As shown in Fig.1a, the pore size become smaller with the increases of BET surface area, and the high surface area may be contributed to high synthesize temperature and long synthesize time. Secondly, we use the as-prepared ATO samples as catalysts support for IrO2, the catalysts named as BET surface area-IrO2 (e.g. 107-IrO2) and the IrO2 loading is 40 wt%. Fig.1b shows the cyclic voltammetry (CV) performance of different catalysts, it is quite clear that when supported by ATO, the voltammograms of these supported catalysts are dissimilar in shape from that of unsupported IrO2. The electrochemically active surface area (ECSA) of 170-IrO2 is obvious higher than the other ATO supported catalyst and a little higher than pure IrO2. This indicate that the 170 sample has the appropriate surface area as well as pore size distribution and it is best used as for IrO2 catalyst support. Finally, the accelerated degradation testing (ADT) was performed to investigated the durability of the 170-IrO2 catalyst in rotating disk electrode (RDE) test. As shown in Fig.1c the CV curves almost overlap before and after 9000 cycles’ ADT. Fig.1d shows the Linear sweep voltammetry (LSV) results of the catalyst samples before and after ADT. It is quite obvious that the 170-IrO2 catalyst is maintained stable with only a little loss in the catalytic activity. We have successfully made a series of ATO through templating process followed by hydrothermal method with different BET surface area and used as catalyst support for IrO2. The 170-IrO2 catalyst demonstrates high electrochemical performance and good stability. Herein, the as-synthesized ATO is considered to be a promising oxygen evolution catalyst support for solid polymer electrolyte water electrolyzer applications. Figure 1