Visible Light Photocatalytic Hydrogen Generation From Water Reduction Over Bi-component Non-Pt Cocatalyst-carbon Nanotubes-Eosin Y

With the rapid development of industrial technology, energy shortage and environmental pollution have become two main problems needed to be solved. Photocatalytic hydrogen generation using solar energy is one of the effective ways to solve the two problems. In it, it is vital to find a new catalyst with high activity of hydrogen evolution. Carbon nanotubes possessed high specific area and unique hollow tubular structure have special properties of chemistry, physics, electronics and mechanics. So they have been applied in many fields. It was reported that carbon nanotubes exhibited excellent performance when they were used as the catalyst support, cocatalyst, or catalyst. In this work, MWNTs was chosen as a matrix and transfer channel of electrons, bi-component non-Pt oxides as the cocatalyst, Eosin Y as a sensitizer in order to obtain the photocatalysts with visible light hydrogen evolution activity. Various factors on photocatalytic activities were discussed in detail. The main contents are as follows.The CuO/NiO-MWNTs was synthesized by soakage and thermal decomposition processes. Using Eosin Y as a sensitizer, the influences of the loading amount of CuO and NiO, the ratio of CuO and NiO, the concentration of TEOA, the pH value and the dosage of Eosin Y on the photocatalytic activity of CuO/NiO-MWNTs photocatalyst were investigated. The results showed that the photocatalytic activitiy of the CuO/NiO-MWNTs-Eosin Y in pH= 7, 15%(vol) of TEOA aqueous solution was the highest when the ratio of CuO and NiO is 1:1, the loading amount of CuO and NiO was 6%, the molar ratio of Eosin Y and CuO/NiO-MWNTs was 1:1. In the optimized conditions, the apparent quantum yield of the photocatalyst was 0.47%(λ=450-550 nm).The Ni/NiO-MWNTs was prepared by reducing NiO-MWNTs in hydrogen atmosphere. The visible light photocatalytic activity of the Ni/NiO-MWNTs-Eosin Y photocatalyst for hydrogen generation from water reduction was investigated. The results indicated that NiO can be reduced to Ni by calcined in hydrogen atmosphere. The photocatalytic hydrogen evolution activity of the Ni/NiO-MWNTs-Eosin Y was obviously improved compared to that of the NiO-MWNTs-Eosin Y. The loading amount of Ni/NiO, dosage of catalysts and pH value all had greatly influences on the hydrogen evolution activity of the Ni/NiO-MWNTs-Eosin Y photocatalyst. In the optimized conditions, the rate of hydrogen production was 344μmol·g-1·h-1, and the apparent quantum yield can arrive at 0.16%(λ= 450-550 nm). The CuO and CoO co-loaded MWNTs were synthesized by soakage and thermal decomposition processes. The photocatalytic activity of the photocatalyst was investigated by using Eosin Y as a sensitizer and triethanolamine as a sacrificial agent. Moreover, the effects of various factors on photocatalytic activity of the Eosin Y sensitized CuO/CoO-MWNTs were studied. When the pH value was 7, the concentration of TEOA was 15%(vol), the loading amount of CuO and CoO was 2%(nCuO:nCoO= 1:1), the ratio of Eosin Y and CuO/CoO-MWNTs was 1:1, the rate of hydrogen production was the fastest, and it can reach 403.1μmol·g-1·h-1, the apparent quantum yield was 0.19%(λ=450-550 nm).In this paper, several di-components non-Pt cocatalyst-carbon nanotubes-Eosin Y photocatalysts with higher activity of hydrogen production were obtained. The cheap and effective cocatalysts, CuO/NiO, Ni/NiO and CuO/CoO were expected to be the suitable candidates and to replace the noble metals such as Pt.