Morphology control of the hematite photoanodes for photoelectrochemical water splitting. (13th November 2020)

• Record Type: Journal Article
• Authors: Wang, Yujie; Rong, Mingyue; Zheng, Jiandong; Rui, Zebao
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 56(2020)
• Page Start: 31667
• Page End: 31677
• Publication Date: 2020-11-13
• Subjects: Hematite -- Nanorod -- Nanowire -- Nanocube -- Photoanode -- Photoelectrochemical water splitting; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.08.230
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The morphology of hematite photoanode is a significant relevant factor in its photoelectrochemical (PEC) performance. Hematite nanowires and nanocubes as well as nanorods with intentional Sn doping were prepared by hydrothermal processes containing disparate additives. The band-gap decreases in the sequence of nanowires, nanorods and nanocubes. Compared with nanorods, nanowires show higher carrier density but a lower light absorbance. With both inhibited bulk and surface charge recombination, nanowires achieve an enhanced photocurrent. Meanwhile, it is more complicated for the charge conversion in the hematite nanocubes. Light absorption is limited due to the compact arrangement of nanocubes. Besides, nanocubes show a highly oriented (104) plane which is unfavorable to the charge conductivity. Despite the negative factors hindering its PEC performance, the extremely high carrier density in the nanocubes benefits to the distinctly enhanced photocurrent collected from the hematite samples annealed at 550 and 650 °C respectively. However, the superiority of hematite nanocubes annealed under 800 °C is restricted by the high onset potential. Still, attributed to the high surface charge transfer efficiency, the hematite nanocubes achieve the highest photocurrent among the samples at biases above 1.3 V. Electrodes made of hematite nanorods, nanowires and nanocubes annealed at 800 °C achieve a photocurrent of 1.01, 1.30 and 1.40 mA cm −2 at 1.6 V vs. RHE, respectively. Graphical abstract: Image 1 Highlights: Hematite nanorods, nanowires and nanocubes were prepared hydrothermally. Light absorbance decreases in sequence of nanorods, nanowires and nanocubes. Hematite nanowires show exceeding PEC performance over the typical nanorods. Hematite nanocubes overtake nanorods and nanowires in performance at high bias. Hematite nanorods nanocubes achieved a photocurrent of 1.40 mA cm −2 at 1.6 V vs. RHE.