We demonstrate for the first time the application of p-NiFe₂O₄/n-Fe₂O₃ composite thin films as anode materials for light-assisted electrolysis of water. The p-NiFe₂O₄/n-Fe₂O₃ composite thin films were deposited on planar fluorinated tin oxide (FTO)-coated glass as well as on 3D array of nanospike (NSP) substrates. The effect of substrate (planar FTO and 3D-NSP) and percentage change of each component (i.e., NiFe₂O₄ and Fe₂O₃) of composite was studied on photoelectrochemical (PEC) water oxidation reaction. This work also includes the performance comparison of p-NiFe₂O₄/n-Fe₂O₃ composite (planar and NSP) devices with pure hematite for PEC water oxidation. Overall, the nanostructured p-NiFe₂O₄/n-Fe₂O₃ device with equal molar 1:1 ratio of NiFe₂O₄ and Fe₂O₃ was found to be highly efficient for PEC water oxidation as compared with pure hematite, 1:2 and 1:3 molar ratios of composite. The photocurrent density of 1:1 composite thin film on planar substrate was equal to 1.07 mA/cm² at 1.23 V_RHE, which was 1.7 times higher current density as compared with pure hematite device (0.63 mA/cm² at 1.23 V_RHE). The performance of p-NiFe₂O₄/n-Fe₂O₃ composites in PEC water oxidation was further enhanced by their deposition over 3D-NSP substrate. The highest photocurrent density of 2.1 mA/cm² at 1.23 V_RHE was obtained for the 1:1 molar ratio p-NiFe₂O₄/n-Fe₂O₃ composite on NSP (NF1-NSP), which was 3.3 times more photocurrent density than pure hematite. The measured applied bias photon-to-current efficiency (ABPE) value of NF1-NSP (0.206%) was found to be 1.87 times higher than that of NF1-P (0.11%) and 4.7 times higher than that of pure hematite deposited on FTO-coated glass (0.044%). The higher PEC water oxidation activity of p-NiFe₂O₄/n-Fe₂O₃ composite thin film as compared with pure hematite is attributed to the Z-path scheme and better separation of electrons and holes. The increased surface area and greater light absorption capabilities of 3D-NSP devices result in further improvement in catalytic activities.

中文翻译：

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的纳米纹理尖峰的α-Fe ₂ ö ₃ /的NiFe ₂ ø ₄复合水的高效光电化学氧化

我们首次证明了p-NiFe ₂ O ₄ / n-Fe ₂ O ₃复合薄膜作为光辅助电解水的阳极材料的应用。将p-NiFe ₂ O ₄ / n-Fe ₂ O ₃复合薄膜沉积在平面氟化氧化锡（FTO）涂层的玻璃上以及纳米钉（NSP）基板的3D阵列上。基材（平面FTO和3D-NSP）的影响以及每种成分（即NiFe ₂ O ₄和Fe ₂ O ₃）的百分比变化）在光电化学（PEC）水氧化反应上进行了研究。这项工作还包括对具有纯赤铁矿的p-NiFe ₂ O ₄ / n-Fe ₂ O ₃复合材料（平面和NSP）装置进行PEC水氧化的性能比较。总体而言，纳米结构的p-NiFe ₂ O ₄ / n-Fe ₂ O ₃器件具有等摩尔比例1：1的NiFe ₂ O ₄和Fe ₂ O ₃比率与纯赤铁矿，复合物的摩尔比为1：2和1：3相比，发现PHA对PEC水氧化具有很高的效率。平面基板上1：1复合薄膜的光电流密度在1.23 V _RHE时等于1.07 mA / cm ²，是纯赤铁矿器件（在1.23 V _RHE时为0.63 mA / cm ²）的电流密度的1.7倍。。通过在3D-NSP衬底上沉积p-NiFe ₂ O ₄ / n-Fe ₂ O ₃复合材料，PEC水氧化性能得到了进一步提高。对于1：1摩尔比的p-NiFe，在1.23 V _RHE时可获得2.1 mA / cm ²的最高光电流密度NSP（NF1-NSP）上的₂ O ₄ / n-Fe ₂ O ₃复合材料，其光电流密度是纯赤铁矿的3.3倍。测得的NF1-NSP（0.206％）的施加偏置光子电流效率（ABPE）值是NF1-P（0.11％）的1.87倍，是沉积在其上的纯赤铁矿的4.7倍。 FTO涂层玻璃（0.044％）。p-NiFe ₂ O ₄ / n-Fe ₂ O ₃的较高的PEC水氧化活性与纯赤铁矿相比，这种复合薄膜归因于Z路径方案以及电子和空穴的更好分离。3D-NSP设备增加的表面积和更大的光吸收能力导致催化活性的进一步提高。