마이크로전자및패키징학회지 (Journal of the Microelectronics and Packaging Society)

  • 제27권2호
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  • Pages.33-38
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  • 2020
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  • 1226-9360(pISSN)
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  • 2287-7525(eISSN)
한국마이크로전자및패키징학회 (The Korean Microelectronics and Packaging Society)
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산소발생용 Cobalt-phosphate (Co-pi) 촉매를 이용한 Gallium Nitride (GaN) 광전극의 광전기화학적 특성

Photoelectrochemical Properties of Gallium Nitride (GaN) Photoelectrode Using Cobalt-phosphate (Co-pi) as Oxygen Evolution Catalyst

  • 성채원 (전남대학교 화학공학부) ;
  • 배효정 (전남대학교 광전자융합기술연구소) ;
  • ;
  • 하준석 (전남대학교 화학공학부)
  • Seong, Chaewon (Department of Advanced Chemicals & Engineering, Chonnam National University) ;
  • Bae, Hyojung (Optoelectronics Convergence Research Center, Chonnam National University) ;
  • Burungale, Vishal Vilas (Department of Advanced Chemicals & Engineering, Chonnam National University) ;
  • Ha, Jun-Seok (Department of Advanced Chemicals & Engineering, Chonnam National University)
  • 투고 : 2020.06.12
  • 심사 : 2020.06.26
  • 발행 : 2020.06.30
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초록

광전기화학적 물분해에서 광전극으로 이용되는 GaN은 전해질에 대해 높은 안정성을 가지고 있으며 물의 산화 환원준위를 포함하고 있어 외부전압 없이 물분해가 가능하다. 그러나 GaN 광전극의 경우, 재료 자체의 효율이 낮아 상용화하기에는 부족한 실정이다. 본 연구에서는 광효율을 향상시키기 위해 Cobalt phosphate(Co-pi) 촉매를 광전기증착(Photoelectro-deposition)방법을 통하여 GaN 광전극에 도입하였다. Co-pi 촉매 증착 후 SEM, EDS, XPS분석을 진행하여 Co-pi의 증착 여부 및 증착 정도를 확인하고, Potentiostat를 이용해 PEC 특성을 분석하였다. SEM 이미지를 통해 Co-pi가 GaN 표면 위에 20~25 nm 사이즈의 클러스터 형태로 고르게 증착되어 있는 것을 확인하였다. EDS 및 XPS 분석을 통해 GaN 표면의 입자가 Co-pi임을 확인하였다. 이 후 측정된 PEC 특성에서 Co-pi를 증착 시킨 후 0.5 mA/㎠에서 0.75 mA/㎠로 향상된 광전류밀도 값을 얻을 수 있었다. 향상된 원인을 밝히기 위하여, 임피던스 및 Mott-Schottky 측정을 진행하였고, 측정 결과, 50.35 Ω에서 34.16 Ω으로 감소한 분극저항(Rp)과 증가된 donor 농도(ND) 값을 확인하였다. 물분해 전 후, 표면 성분을 분석한 결과 물분해 후에도 Co-pi가 남아있음으로써 Co-pi 촉매가 안정적이라는 것을 확인하였다. 이를 통해, Co-pi가 GaN의 효율 향상을 위한 촉매로서 효과가 있음을 확인하였고, 다른 광전극에 촉매로써 적용시켰을 경우, PEC 시스템의 효율을 향상시킬 수 있을 것으로 판단된다.

In the photoelectrochemical (PEC) water splitting, GaN is one of the most promising photoanode materials due to high stability in electrolytes and adjustable energy band position. However, the application of GaN is limited because of low efficiency. To improve solar to hydrogen conversion efficiency, we introduce a Cobalt Phosphate (Co-pi) catalyst by photo-electrodeposition. The Co-pi deposition GaN were characterized by SEM, EDS, and XPS, respectively, which illustrated that Co-pi was successfully decorated on the surface of GaN. PEC measurement showed that photocurrent density of GaN was 0.5 mA/㎠ and that of Co-pi deposited GaN was 0.75 mA/㎠. Impedance and Mott-Schottky measurements were performed, and as a result of the measurement, polarization resistance (Rp) and increased donor concentration (ND) values decreased from 50.35 Ω to 34.16 Ω were confirmed. As a result of analyzing the surface components before and after the water decomposition, it was confirmed that the Co-pi catalyst is stable because Co-pi remains even after the water decomposition. Through this, it was confirmed that Co-pi is effective as a catalyst for improving GaN efficiency, and when applied as a catalyst to other photoelectrodes, it is considered that the efficiency of the PEC system can be improved.

키워드

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