In 2012, I printed my first Ta3N5-related paper in Superior Supplies [1], reporting a Ta3N5 nanorod photoanode with a hall-cell solar-to-hydrogen effectivity (HC-STH) of 0.37%. Coming into the photoelectrochemical (PEC) water splitting subject with a background in nanomaterials, my motivation at the moment was to make the most of 1D nanostructure to enhance the sunshine absorption and cost assortment in Ta3N5 photoanode. However, the opposite effectivity figuring out components, such because the floor defects and the oxygen evolution response (OER) co-catalyst, had been removed from optimized. By doping the Ta3N5 nanorod with Ba and modifying it with a Co-Pi OER co-catalyst, we considerably improved the HC-STH of the nanorod photoanode to 1.56% [2].
In 2016, Prof. Can Li’s group at DICP proposed a novel hole-storage idea to mediate interfacial cost switch from Ta3N5 to coupled molecular catalysts [3]. This built-in Ta3N5 photoanode achieved a powerful photocurrent of 12.1 mA cm-2 at 1.23 V vs. RHE, approaching its theoretical photocurrent restrict beneath daylight (12.9 mA cm-2). Owing to the excessive photocurrent, the HC-STH of the Ta3N5 photoanode was boosted to 2.5%. In 2020, Prof. Kazunari Domen’s group additional improved the HC-STH of Ta3N5 photoanode to 2.72% by designing a Ta3N5 nanorod construction to reinforce gentle harvesting and cost assortment [4].
Since beginning my unbiased analysis in 2016, my group at UESTC has been dedicated to enhancing the effectivity of Ta3N5 skinny movie photoanode by way of band construction engineering, defect engineering, and interface engineering. By developing a gradient band construction within the bulk of Ta3N5 skinny movie via gradient Mg-doping, we achieved an HC-STH of three.31% due to the improved bulk cost separation effectivity within the gradient Mg-doped Ta3N5 photoanode [5]. Alternatively, by modifying the interfaces of Ta3N5 skinny movie with an electron transport layer (ETL: In-doped GaN) and a gap transport layer (HTL: Mg-doped GaN), we realized a heterostructured Ta3N5 photoanode with an HC-STH of three.46% [6]. Currently, we demonstrated a heterogeneous doping technique that mixed floor La doping with bulk gradient Mg doping in Ta3N5 skinny movie to decouple gentle absorption and service transport, leading to a record-high HC-STH of 4.07% for Ta3N5 photoanode [7], ten instances greater than what had been achieved a decade in the past [1]. These outcomes established Ta3N5 as a number one performer amongst seen‐gentle‐responsive photoanodes for PEC water splitting.
The subsequent huge problem is to additional enhance the STH from the present 4% to a commercially viable effectivity of above 10%, which requires each materials and system improvements. Materials-wise, we consider the bottom line is nonetheless to search out efficient methods to passivate the effectivity limiting deep-level defects in Ta3N5 [8]. System-wise, developing tandem gadgets with appropriate photocathodes might be a extra sensible solution to understand excessive effectivity.
However, tright here continues to be loads of room for enchancment – this shall be the right mindset going ahead.
[1] Li, Y. et al. Vertically aligned Ta3N5 nanorod arrays for solar-driven photoelectrochemical water splitting. Adv. Mater. 25, 125-131 (2013).
[2] Li, Y. et al. Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% photo voltaic power conversion effectivity. Nat. Commun. 4, 2566 (2013).
[3] Liu, G. et al. Enabling an built-in tantalum nitride photoanode to method the theoretical photocurrent restrict for photo voltaic water splitting. Vitality Environ. Sci. 9, 1327-1334 (2016).
[4] Pihosh, Y. et al. Ta3N5-Nanorods enabling extremely environment friendly water oxidation by way of advantageous gentle harvesting and cost assortment. Vitality Environ. Sci. 13, 1519-1530 (2020).
[5] Xiao, Y. et al. Band construction engineering and defect management of Ta3N5 for environment friendly photoelectrochemical water oxidation. Nat. Catal. 3, 932-940 (2020).
[6] Fu, J. et al. Interface engineering of Ta3N5 skinny movie photoanode for extremely environment friendly photoelectrochemical water splitting. Nat. Commun. 13, 729 (2022).
[7] Xiao, Y. et al. Decoupling gentle absorption and service transport by way of heterogeneous doping in Ta3N5 skinny movie photoanode. Nat. Commun. 13, 7769 (2022).
[8] Fu, J. et al. Figuring out performance-limiting deep traps in Ta3N5 for photo voltaic water splitting. ACS Catal. 10, 10316–10324 (2020).