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First-Principles Calculation of Cr/S Co-doped Rutile TiO2

Li Jianning, Wu Fang, Shi Jianying, Ma Lei, Yan Xiaobing, Yang Nan, Ding Bangfu, Zheng Shukai

Materials Science Poland

2020

Vol. 38, No. 2

253--262

The electronic structures and optical properties of pure, Cr, S single- and Cr/S co-doped rutile TiO2 were calculated by the first-principle plane wave pseudopotential method based on density functional theory. The calculated results indicate that the three different doping ways can lead to lattice distortion in the rutile TiO2 and introduce local electronic states in the forbidden band of TiO2. The local energy levels in the forbidden band of TiO2 are mainly contributed by Cr-3d and S-3p orbital. Compared with pure TiO2, the absorption edges (i.e. the edge of the main peak) of the doped TiO2 have different blue shifts; however, the light response ranges of the doped systems are extended, especially in the case of Cr single- and Cr/S co-doped TiO2. The extension of the visible light response range of the doped TiO2 may enhance its visible light photocatalytic performance. In addition, the co-doped TiO2 has a stronger oxidation ability, which may increase the catalytic efficiency of TiO2.

Temporal and Spatial Patterns of Aboveground Biomass and Its Driving Forces in a Subtropical Forest : A Case Study

Ma Lei, Li Wen, Shi Nannan, Fu Shenglei, Lian Juyu, Ye Wanhui

Polish Journal of Ecology

2019

Vol. 67, nr 2

95--104

The accurate characterization of aboveground biomass (AGB) dynamics and their driving forces in sub-tropical forests is important to evaluate AGB's contribution to global carbon stocks. In order to estimate the effects of local variables on temporal and spatial patterns of AGB we investigated the variation of AGB in a 20-ha sub-tropical permanent plot. We found that the AGB was 153.7 Mg ha-1 in 2005, and 149.3 Mg ha-1 in 2010. During the five-year period, AGB changed due to tree mortality, growth (diameter at breast height, DBH) and recruitment. Medium-sized trees (DBH: 30-50 cm) were the largest contributor to total AGB. Both the tree species diversity index and the number of individuals within medium (DBH: 30-50 cm) and large (DBH: >50 cm) DBH ranges had significant positive effects on AGB. In addition, the abiotic factors such as elevation, slope, and convexity had negative significant relationships with AGB. The results indicate the importance of including forest community characteristics and environmental variables in forest carbon studies. This study also provides important data that can be used to develop and validate carbon cycling models for old-growth sub-tropical forests.