It is proved that secondary phases, such as Cu 2 Se, and ZnSe etc., and MoSe 2 layer can form at Cu 2 ZnSn(S,Se) 4 (CZTSSe)/Mo electrode interface, due to that Mo electrode reacts with CZTSSe and Se vapor during selenization process. The secondary phases and MoSe 2 with inappropriate thickness can decrease power conversion efficiency (PCE) of CZTSSe solar cell. In this work, a simple method was proposed to suppress the reaction between CZTSSe and Mo, and to optimize the thickness of MoSe 2 . This was achieved by growing a layer of Mo oxide in situ on the Mo electrode surface through soaking the Mo electrode in H 2 O 2 . The Mo oxide layer consisted of MoO 3 , MoO x and MoO 2 . It could suppress the reaction between Mo and CZTSSe, thus preventing the formation of secondary phases in CZTSSe. By further tuning the soaking time, the thickness and density of the Mo oxide layer were optimized, resulting in an optimized thickness of the MoSe 2 layer and a significant improvement in the contact quality at both the front and back interfaces. This improvement is beneficial for suppressing carrier recombination and reducing contact resistance. Furthermore, the Cu/(Zn+Sn) ratio in CZTSSe was optimized, leading to an expansion of the depletion region width. As a result, the reverse saturation current density and series resistance decrease, while the photogenerated current density increases. This ultimately led to a rise in PCE from 7.66% for CZTSSe solar cells with Mo electrodes that were not soaked to 8.95% for those with Mo electrodes soaked for 20 s.
In this work, three kinds of biochars (PMBC-H 2 O, PMBC-PP and PMBC-HP) with excellent adsorption performance were obtained by carbonizing pig manure pre-treated with different agents. These biochars had the ordered mesoporous structures and possessed abundant active functional groups on their surface. The adsorption behaviors of the biochars towards U VI under various conditions were evaluated by batch experiment. The results showed that KMnO 4 and H 2 O 2 could enormously improve the adsorption performance of PMBC to U VI . After KMnO 4 and H 2 O 2 pretreatment , the maximum adsorption capacities of PMBC-PP (979.3 mg/g) and PMBC-HP (661.7 mg/g) were about 2.6 and 1.8 times higher than that of PMBC-H 2 O (369.9 mg/g), respectively, which was much higher than previously reported biochar-based materials. Obviously, KMnO 4 pretreatment leaded to a higher enhancement than that of H 2 O 2 . The removal mechanism of U VI on PMBC-PP was discussed in-depth. The interaction between U VI species and PMBC-PP was mainly ascribed to the abundant active sites on the surface of PMBC-PP. In a word, conversion of pig manure pre-treated with KMnO 4 into biochar not only demonstrates that PMBC-PP has great potential in the treatment of actual uranium-containing wastewater, but also provides a method for the rational utilization of pig manure to reduce the pollution.
In the study presented herein, a series of TiO2-supported Ru catalysts were prepared through over-impregnation with different amounts of H2O2and applied to the catalytic combustion of dichloromethane (DCM). The experimental results show that the optimal (1 H2O2)-Ru@TiO2catalyst sample yields 90% DCM conversion at 301 °C, which is 40 °C lower than the temperature required by the (0 H2O2)-Ru@TiO2catalyst. This good activity is related to its high number of acid sites (especially Brønsted acid sites), an appropriate amount of uniformly dispersed RuO2particles, and strong interaction between RuO2and the TiO2support. In addition, excessive H2O2leads to the growth and phase segregation of RuO2, which weakens the interaction between RuO2and the TiO2support and decreases catalytic activity. Moreover, H2O2addition also contributes to the stability of catalysts, which possibly results from the re-dispersion of RuO2on the TiO2support during the reaction.
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