Oxygen Evolution Activity on Mo Added Zr Oxide Catalyst in Alkaline Solution

On Sep. 26, 2022, Hydrogen energy ministerial meeting (H 2 EM 2022) was held by the ministry of economy, trade and industry (METI) of Japanese government as online special event with cabinet members and officials from 30 countries, regions, and organizations. In the chair’s summary of meeting, an additional goal also proposed the amount of renewable and low-carbon hydrogen to be produced by 2030 of at least 90Mt H 2 . In the open session, the water electrolysis was one of the main topics of the session, and due to the demand for “Green Hydrogen” as already described in chairman’s summary, installed capacity of water electrolyzer has been required for the huge size of its module [1]. Here, “Green Hydrogen” is the hydrogen which is produced by the electricity from renewable energies introducing in our previous study [2]. Alkaline water electrolysis (AWE) has already commercialized and recently applied its system for the Power-to-Gas (PtG) all over the world. In the Fukushima hydrogen energy research field (FH2R) in Japan, one of the largest module of AWE named “Aqualyzer” has operated from 2020. However, previous literature reported that the degradation of Ni anode occurs operating by variable renewable energy (VNE) [3]. From this point of view, the alternative anode with high durability against VNE should be required for green hydrogen production. We focused on zirconium oxide-based electrocatalyst (ZrO x ) and have studied the catalytic activity of its thin film fabricated by sputtering procedure for oxygen evolution reaction (OER) [4-5]. In this study, we have investigated the OER activity of Mo added ZrO 2 (Mo-ZrO 2 ) fabricated by atomic layer deposition (ALD) and arc plasma deposition (APD) in alkaline solution. Mo-ZrO x was formed on Ti rods as a base material, using by ALD and APD. In the step of ALD, Tetrakis(dimethylamino)zirconium (TDMAZr) and water were used as precursor and oxidant of ZrO 2 , and the substrate was heated at 225 o C. The thickness of ZrO 2 film was 10 nm for preparation. Then, the MoO x was fabricated by APD using Mo metal as target material at 0.74 Pa of partial pressure of oxygen and the substrate was heated at 300 o C. At last, the annealing was performed under Ar atmosphere at 300 o C to produce the Mo-ZrO 2 catalyst. In the case of inserting interlayer, TaO x was formed by the R.F. magnetron sputtering before ALD step. All electrochemical measurements were carried out using a three-electrode cell at 30 o C in 7 M KOH. A reve