製備摻雜氮之二氧化鈦於奈米金柱上作為光電化學分解水之應用

Abstract

在本論文中，我們透過三個實驗步驟製備出高表面積的氮摻雜之二氧化鈦於奈米金柱之複合材料。首先利用電化學沉積法於碳布基材上製備具高表面積的奈米金柱結構 (直徑約 100 – 300 nm，長度約 1-2 m)，接著用水熱法將二氧化鈦成長覆蓋在奈米金柱上，在製備二氧化鈦的過程中，我們藉由改變滴加二氧化鈦之先驅物的次數，來調控二氧化鈦之含量及厚度。最後將最佳化條件之樣品，在氨氣環境下做鍛燒，可得到摻雜氮之二氧化鈦與金奈米柱的複合材料。 在光電流應用量測中，將所製備之複合結構材料分別在紫外可見光及可見光激發下進行光電流量測。在紫外可見光照射下，其中最佳化條件為重複滴加四次先驅物之樣品，進一步於400 oC下做氮摻雜之製備，其光電流值為 4.5 mA/cm2，並且在連續開燈一小時的照射下，電流值可維持在4.4 mA/cm2。而在可見光光源照射下，則可得到40 A/cm2 之光電流，為未做氮摻雜之樣品的光電流值之三倍。

We demonstrated the fabrication of a high surface area hybrid material composed of N-doped TiO2 coated Au nanorods (NRs) on carbon fibre (N-TAC) by a three-step method. Firstly, Au NRs on carbon fibre substrates (AC) were grown by electrochemical deposition. Subsequently, TiO2 was coated on the Au NRs by a hydrothermal method. Then, the material was heat-treated in a NH3 atmosphere to offer N-TAC. The photocatalytic activity of the as-prepared hybrid material N-TAC in photoelectrochemical (PEC) water splitting was investigated by measuring its photocurrent responses under UV-visible (UV-Vis) and visible light irradiations. Under a UV-Vis irradiation, the sample with the highest photocurrent 4.5 mA/cm2 (at 0.2 V vs. Ag/AgCl) initially retained a value 4.4 mA/cm2 after 1 h. Upon visible light illumination, a photocurrent 40 A/cm2 was obtained. The result was a 3-fold increase relative to the value of a TAC sample without NH3 treatment. We propose that the high PEC performance of N-TAC was contributed by the high surface area and the improved conductivity of the Au NRs. In addition, visible light absorption might be enhanced by the presence of the plasmonic effect from the Au NRs. Together, the light harvesting efficiency was improved.