溶凝膠法製備InTaO4光觸媒在水分解產氫研究

Sol-gel prepared InTaO4 in photocatalytic water splitting for hydrogen production

邱怡菁(Yi-Ching Chiou)

指導教授 ： 吳紀聖

國立臺灣大學/工學院/化學工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01686

摘要

InTaO4是一種可見光觸媒用於光催化水分解製氫反應。過去InTaO4光觸媒都是以固態高溫熔融法所製備，其必須在1100 oC以上高溫鍛燒，有混合不均難以形成InTaO4晶相之困難。故本實驗是以In(NO3)3和Ta(OC4H9)5當作初始前驅物，使用溶凝膠法製備而成。因此法是在溶液中進行，故其較能均勻混合，解決固態高溫熔融法混合不均的缺點，且其只需在950 oC鍛燒即可形成InTaO4，但其晶相卻不甚完美。故為了能合成出完全的InTaO4晶相，本研究仍以1100 oC鍛燒。在InTaO4光觸媒表面上含浸不同比例的NiOx共觸媒，經由還原─氧化前處理的活化下，探討其對水分解產生氫氣與氧氣活性的影響。由一系列儀器的檢測結果顯示，溶凝膠法所製備的InTaO4觸媒其顆粒較小、比表面積大、能形成完全InTaO4的晶相。將一系列InTaO4光觸媒進行水分解反應，以on-line GC-TCD測量氫氣與氧氣產率，可得到2:1的氫氧莫耳比。研究發現溶凝膠法製備而成的InTaO4觸媒比固態高溫熔融法製成的觸媒具較高的水分解活性，其中又以含浸3.0 wt.% NiOx/ InTaO4光觸媒具有最高的水分解活性。實驗也發現，當光強度增加時，觸媒的催化活性也隨之增加，但其氫氣速率與光強度並不呈線性關係。

關鍵字

NiOx/ InTaO4光觸媒 ； 光催化水分解 ； 可見光輻射 ； 產氫技術

並列摘要

InTaO4 is a visible light photocatalyst used in water splitting to produce hydrogen. In the past, InTaO4 was usually prepared by the solid- state fusion method at high temperatures. The catalyst must be sintered at 1100 oC or above, however the solid-state fusion method gives poor InTaO4 crystal structure. In(NO3)3 and Ta(OC4H9)5 precursors was used in the sol-gel method. Since the sol-gel method allows liquid-phase mixing, it solves the problem of poor mixing using the solid-state fusion method, thus a calcination temperature of 950 oC to form InTaO4 is required. However the crystallinity is not perfect, thus in order to achieve better InTaO4 crystallinity a calcination temperature of 1100 oC was used in this work . The activities of various weight loadings of NiOx on InTaO4 catalyst surface was investigated in water splitting to produce hydrogen and oxygen. A series of catalyst characterization results showed that InTaO4 catalyst prepared by the sol-gel method gives particles smaller in size, larger surface area and a pure InTaO4 crystal structure. Using InTaO4 photocatlayst in water splitting with an online GC system equipped with TCD detector to detect hydrogen and oxygen concentrations showed that a mole ratio of 2:1 was achieved. The results indicate that InTaO4 prepared by the sol-gel method gives higher activity than catalysts prepared by the solid-state fusion method. Among all the photocatalysts, 3.0 wt.% NiOx/ InTaO4 had the highest photo-activity. An increase in light intensity increased the photocatalyst activity. However this relationship is not linear.

並列關鍵字

NiOx/ InTaO4 photocatalyst ； photocatalytic water splitting ； visible light irradiation ； hydrogen evolution

參考文獻

1. A. Fujishima, K. Honda, Electrochemical photolysis of water at a semiconductor electrode, Nature, 238 (1972) 37-38.

2. J. Ye, Z. Zou, H. Arakawa, M. Oshikiri, M. Shimoda, A. Matsushita, T. Shishido, Correlation of crystal and electronic structures with photophysical properties of water splitting photocatalysts InMO4 (M = V5+, Nb5+, Ta5+), Journal of Photochemistry and Photobiology A: Chemistry, 148 (2002) 79–83.

3. K. Domen, A. Kudo, T. Onishi, N. Kosugi, Haruo Kuroda, Photocatalytic Decomposition of Water Into H2 and O2 over NIO-SrTiO3 Powder. 1. Structure of the Catalyst, Journal of Physical Chemistry, 90 (1986) 292-295

4. A. Kudo, A. Tanaka, K. Domen, K.-i. Maruya, K.-i. Aika, T. Onishi, Photocatalytic Decomposition of Water over NiO-K4Nb6O17 Catalyst, Journal of Catalysis, 111 (1988) 67-76.

5. C. T. K. Thaminimulla, T. Takata, M. Hara, J. N. Kondo, K. Domen, Effect of chromium addition for photocatalytic overall water splitting on Ni-K2La2Ti3O10, Journal of Catalysis, 196 (2000) 362-365.