Maximizing Oxygen Evolution Performance on a Transparent NiFeOx/Ta3N5 Photoelectrode Fabricated on an Insulator
Maximizing Oxygen Evolution Performance on a Transparent NiFeOx/Ta3N5 Photoelectrode Fabricated on an Insulator
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DOI：
10.1021/acsami.1c00826
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发表时间：
2021-04-02
影响因子：
9.5
通讯作者：
Takanabe, Kazuhiro
中科院分区：
文献类型：
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作者：
Kawase, Yudai;Higashi, Tomohiro;Takanabe, Kazuhiro
透明Ta 3 N5光阳极是一种很有前途的候选人的前侧光电极在光电化学（PEC）电池与串联配置（串联电池），这可能会提供高的太阳能-氢气（STH）能量转换效率。本研究特别关注在绝缘石英衬底（Ta 3 N5/SiO2）上制造的透明Ta 3 N5光阳极的半导体特性和界面设计，通常在其边缘上与铟接触的几何面积为1 x 1 cm（2）。这种材料利用Ta 3 N5的自导电性来使PEC系统工作，并且电极将强烈反映Ta 3 N5的固有性质，而没有通常引入的背接触。首先，使用乙腈（ACN）/H2O混合溶液进行PEC测量，以阐明三（2，2 '-联吡啶）钌（II）双（六氟磷酸盐）（Ru-（bpy）（3）（PF 6）（2））存在下的固有光响应，而不接触水，这避免了多电子转移析氧反应（OER）和光诱导自氧化。Ta 3 N5/SiO2氧化Ru 2 + PEC的起始电位与Ru 2 +/3+在非水环境中的氧化还原电位之间的电位差约为0.7 V。虽然在非水相中观察到Ta 3 N5/SiO2的稳定的光阳极响应，在该非水体系中加入少量水，可使Ta_3N_5/Al_2O_3体系立即失活。SiO2光阳极在光照下通过自光氧化在固体/水界面形成TaOx。在水相中，由Mott-Schottky分析估计的平带电位随溶液pH而变化（对可逆氢电极（RHE）的恒定电位）。尝试通过透明NiFeOx层的光电极改性。通过使用受控Ni-Fe前体的优化旋涂方案实现的透明NiFeOx电催化剂对Ta 3 N5表面的完全覆盖，允许成功保护Ta 3 N5，并在没有任何额外保护层的情况下表现出数小时内极其稳定的光电流。所得NiFeOx/Ta 3 N5/SiO2的稳定性不受Ta 3 N5的限制，而是主要受由于Fe随时间溶解的NiFeOx电催化剂的限制。
A transparent Ta3N5 photoanode is a promising candidate for the front-side photoelectrode in a photoelectrochemical (PEC) cell with tandem configuration (tandem cell), which can potentially provide high solar-to-hydrogen (STH) energy conversion efficiency. This study focuses in particular on the semiconductor properties and interfacial design of transparent Ta3N5 photoanodes fabricated on insulating quartz substrates (Ta3N5/SiO2), typically the geometric area of 1 x 1 cm(2) in contact with indium on its edge. This material utilizes the self-conductivity of Ta3N5 to make the PEC system operational, and the electrode would strongly reflect the intrinsic nature of Ta3N5 without a back contact that is commonly introduced. First, PEC measurements using acetonitrile (ACN)/H2O mixed solution were made to elucidate the intrinsic photoresponse in the presence of tris(2,2'-bipyridine)ruthenium(II) bis(hexafluorophosphate) (Ru-(bpy)(3)(PF6)(2)) without water contact which avoids a multielectron-transfer oxygen evolution reaction (OER) and photoinduced self-oxidation. The potential difference between the onset potential of Ru2+ PEC oxidation by Ta3N5/SiO2 and the redox potential of Ru2+/3+ in the nonaqueous environment was about 0.7 V. While a stable photoanodic response was observed for Ta3N5/SiO2 in the nonaqueous phase, the addition of a small quantity of water into this nonaqueous system led to the immediate deactivation of Ta3N5/SiO2 photoanode under illumination by self-photooxidation to form TaOx at the solid/water interface. In aqueous phase, flatband potentials estimated from Mott-Schottky analysis varied with solution pH (constant potential against reversible hydrogen electrode (RHE)). Photoelectrode modification by a transparent NiFeOx layer was attempted. The complete coverage of the Ta3N5 surface with transparent NiFeOx electrocatalysts, achieved by an optimized spin-coating protocol with controlled Ni-Fe precursors, allowed for the successful protection of Ta3N5 and demonstrated an extremely stable photocurrent for hours without any additional protective layers. The stability of the resultant NiFeOx/Ta3N5/SiO2 was limited not by Ta3N5 but mainly by a NiFeOx electrocatalyst due to Fe dissolution with time.