Abstract

The use of hematite as a photoanode has been limited due to its optoelectronic properties and a large overpotential for photo-assisted water splitting. In this study, a cobalt-phosphate (Co–Pi) layer was deposited on hematite photoanodes (α-Fe₂O₃) in order to increase the lifetime of the photogenerated holes and to lower the applied bias. The influence of the Co–Pi catalyst thickness, the pH of deposition, and the scan rate of the photoelectrochemical (PEC) measurements were optimized using the Taguchi statistical method. An L9 orthogonal array, with the three factors of control at three levels, was employed to determine the optimum conditions for water splitting of neutral water with minimum applied bias. After depositing Co‒Pi layer on the α-Fe₂O₃ at different conditions, the PEC was measured via the linear sweep voltammetry (LSV) and chronoamperometry. The analysis of variance of the mean overpotential in comparison with the bare hematite and the signal-to-noise ratio indicated the great influence of catalyst thickness on the decreasing of overpotential for photo-assisted water splitting in comparison with the bare α-Fe₂O₃. The characterization of the catalyst and the α-Fe₂O₃ morphology were carried out by SEM, XRD, and EDS. The optimized photoanode showed an enhancement of around two times for photocurrent and 1.5 times in incident photon-to-current conversion efficiency (IPCE) compared to the bare α-Fe₂O₃. These findings result in an understanding of the role of the Co–Pi catalyst role in improving the hematite photoanode.

中文翻译：

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Taguchi方法在水分解应用中优化Co-Pi /α-Fe2 O 3催化剂的合成参数

摘要

由于赤铁矿的光电特性和光辅助水分解的过大电势，其用途受到了限制。在这项研究中，钴-磷酸盐（联合PI）层沉积在赤铁矿光阳极（的α-Fe ₂ ö ₃中为了提高光生空穴的寿命，并降低所施加的偏置）。使用Taguchi统计方法优化了Co-Pi催化剂厚度，沉积的pH值和光电化学（PEC）测量扫描速率的影响。一个L9正交阵列，其中三个控制因子在三个级别上，用于确定中性水的水分解的最佳条件，并施加最小的偏压。上的α-Fe沉积共裨层后₂ ö_{如图3所示，}在不同条件下，通过线性扫描伏安法（LSV）和计时电流法测量PEC。平均过电位的方差与裸赤铁矿和信噪比的比较分析表明与裸的α-Fe的比较上的超电势为光辅助水分解的减少催化剂厚度的影响很大₂ ö ₃。催化剂和α-Fe的表征₂ ö ₃形态进行了通过SEM，XRD和EDS进行。优化的光电阳极显示出的光电流为围绕两个倍和1.5倍的增强在入射光子-电流比裸转换效率（IPCE）的α-Fe ₂ ö ₃。这些发现使人们了解了Co-Pi催化剂在改善赤铁矿光阳极中的作用。