Publication: The effect of various parameters on the photoelectrochemical hydrogen production performance of photoelectrodes
Abstract
Küresel popülasyonun artması ve ekonomik kalkınmanın hızlanması, enerji üretim gerekliliğini ve enerji üretiminde yoğun olarak kullanılan fosil yakıt kaynaklarının miktarını azaltmıştır. Fosil yakıt yakımından kaynaklanan ve atmosfere salınan gazlar çevreye ve insan sağlığına büyük zarar vermektedir. Temiz bir alternatif olan hidrojen üretimi ve bu üretimi güneş ışığı varlığında fotoelektrokimyasal yolla yapmak çevresel kaygılara ve enerji ihtiyacına çözüm üretebilir. Fotoelektrokimyasal çalışmalarda, optimum parametreleri kullanarak en etkili fotoelektrotları geliştirmek önem taşımaktadır. Bu çalışmada CdZnS, CdZnSSe, CdZnNiSSe, CdZnCuSSe, CdZnMoSSe fotoelektrotlarının tek aşamalı elektrodepozisyonu ve indirgenmiş grafen oksit (RGO)’in hazırlanan bu fotoelektrotlar üzerindeki etkisi literatürde ilk kez incelenmiştir. Elektrokimyasal depozisyon ile fotoelektrot üretimi tekrarlı dönüşümlü voltametri yöntemi ile sağlanmıştır. Fotoelektrotların fotoelektrokimyasal özellikleri üç elektrotlu sistem ile incelenmiştir. Fotoelektrokimyasal performansı incelemek için açık devre potansiyeli, doğrusal taramalı voltametri, kronoamperometri, UV-vis difüz reflektans spektroskopisi, elektrokimyasal empedans spektroskopisi ve Mott-Schottky analizleri uygulanmıştır. Varılan sonuçlarla, kullanılan kalkojenlerin fotoelektrottaki kompozisyonlarının, tavlama sıcaklığının, RGO konsantrasyonunun optimize edilmesi elektron-hol rekombinasyonunun ve fotokorozyonun önlenmesini sağlayarak performansı artırmaktadır. Çalışmanın başında bulunan fotoakım yoğunluğu 25 µA cm-2 (ZnS) iken, yapılan modifikasyonlar sonucu bu değer 5.34 mA cm-2 ‘a (RGO(0.25)- Cd0.6Zn0.2Ni0.2S0.2Se0.8) yükselmiştir. Maksimum uygulanan bias ışıktan akım eldesi verimi RGO(0.25)-Cd0.6Zn0.2Ni0.2S0.2Se0.8 fotoelektrotu için %3.18 olarak tespit edilmiştir
The global population expansion and economic improvement have brought about problems such as increasing energy demand and diminishing fossil fuels. Moreover, harmful emissions due to the combustion of fossil fuels are released into the atmosphere having a negative impact on human health and environment. To overcome this handicap, the photoelectrochemical hydrogen generating process has a tremendous deal of potential. The key factor in photoelectrochemical studies is modifying the most effective photoelectrodes using the optimum parameters and the appropriate deposition methods. This study reports the one-step electrodeposition of CdZnS, CdZnSSe, CdZnNiSSe, CdZnCuSSe, CdZnMoSSe and the effect of reduced graphene oxide (RGO) decoration on the photoelectrochemical performance of fabricated photoelectrodes for the first time in the literature. Electrochemical deposition was carried out via repetitive cyclic voltammetry at room temperature. Photoelectrodes were annealed and their photoelectrochemical performances were investigated. To interpret their photoelectrochemical performance and efficiency, open circuit potential measurements, linear sweep voltammetry, chronoamperometry, UV-vis diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, Mott-Schottky analyses were performed. The results demonstrated that optimizing the concentrations of the chalcogenides, annealing temperature, and RGO concentration decreased the rate of electron-hole recombination avoiding photocorrosion. Finally, the photocurrent density is increased from 25 µA cm-2 (ZnS) to 5.34 mA cm-2 (RGO(0.25)- Cd0.6Zn0.2Ni0.2S0.2Se0.8) as a result of modifications. The maximum applied bias photonto-current efficiency (ABPE) was estimated as 3.18% for RGO-Cd0.6Zn0.2Ni0.2S0.2Se0.8 photoelectrodes
The global population expansion and economic improvement have brought about problems such as increasing energy demand and diminishing fossil fuels. Moreover, harmful emissions due to the combustion of fossil fuels are released into the atmosphere having a negative impact on human health and environment. To overcome this handicap, the photoelectrochemical hydrogen generating process has a tremendous deal of potential. The key factor in photoelectrochemical studies is modifying the most effective photoelectrodes using the optimum parameters and the appropriate deposition methods. This study reports the one-step electrodeposition of CdZnS, CdZnSSe, CdZnNiSSe, CdZnCuSSe, CdZnMoSSe and the effect of reduced graphene oxide (RGO) decoration on the photoelectrochemical performance of fabricated photoelectrodes for the first time in the literature. Electrochemical deposition was carried out via repetitive cyclic voltammetry at room temperature. Photoelectrodes were annealed and their photoelectrochemical performances were investigated. To interpret their photoelectrochemical performance and efficiency, open circuit potential measurements, linear sweep voltammetry, chronoamperometry, UV-vis diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, Mott-Schottky analyses were performed. The results demonstrated that optimizing the concentrations of the chalcogenides, annealing temperature, and RGO concentration decreased the rate of electron-hole recombination avoiding photocorrosion. Finally, the photocurrent density is increased from 25 µA cm-2 (ZnS) to 5.34 mA cm-2 (RGO(0.25)- Cd0.6Zn0.2Ni0.2S0.2Se0.8) as a result of modifications. The maximum applied bias photonto-current efficiency (ABPE) was estimated as 3.18% for RGO-Cd0.6Zn0.2Ni0.2S0.2Se0.8 photoelectrodes