Yuanling Li,Han Yu,Jing Dai,Zhenzong Zhang,Zhichao Zhang,Hongbing Yu,Lina Liu
Non-thermal plasma (NTP) combined with catalysts supplies a potential alternative to enable the CH 4 and CO 2 conversion to work at low temperatures. In this study, different Ni/BN catalysts were synthesized using modified wetness impregnation for CH 4 and CO 2 conversion in dielectric barrier discharge (DBD) plasma. Among, BN_IPA_Ni exhibited the highest catalytic performance with a CH 4 conversion of 40.5%, a CO 2 conversion of 26.6%, a H 2 yield of 9.3% and a CO yield of 10.5%. The development of B O defects, which played a significant role in the size control of Ni particles to facilitate the dissociation of CH 4 to form H*, is the key for the high catalysis activity and selectivity in this reaction. In addition, the B O defects of BN_IPA_Ni provide an efficient route to eliminate excess CH x species, which further inhibit the nucleation growth of carbon species to inert carbon.
Fe-modified Ni/Al 2 O 3 catalysts with Fe/Ni molar ratios of 0, 0.5, 1 and 2 were prepared to promote the co-production of H 2 and carbon nanotubes (CNTs) during steam reforming of toluene as a tar model compound. After the addition of Fe, toluene conversion increased from 55.1% of Ni/Al 2 O 3 to 73.6% of F1N1A (Fe/Ni ratio of 1), and H 2 yield over F1N1A reached the maximum of more than 2000 mmol/(g-cata). Multi-walled carbon nanotubes with average diameter of 10–30 nm were generated and follow tip-growth mechanism. Compared with Ni/Al 2 O 3 , the addition of Fe remarkably increased the amount and quality of CNTs which had longer length and less tortuosity. These dual promoting effects on H 2 and CNTs after the addition of Fe were attributed to the strong interaction between Ni and Fe in Fe-Ni alloy. Fe-Ni alloy had the high activity for the decomposition performance of toluene and H 2 O to generate more H 2 and intermediates for improving the reforming reaction. Meanwhile, the high catalytic decomposition activity supplied more carbon species and the formation of Fe-Ni alloy enhanced the generation of metal carbide for promoting CNTs growth. Besides, the deposition of amorphous carbon was suppressed and the interaction between Ni particle and catalyst support was weakened after the addition of Fe, which kept the activity of catalyst and promoted the tip-growth of CNTs.
Ziyu Xie,Jing Chen,Yanxin Chen,Tianming Wang,Xia Jiang,Yiming Xie,Can-Zhong Lu
Pd modified ZnIn 2 S 4 /P25 (Pd@ZnIn 2 S 4 /P25) heterostructures have been synthesized by hydrothermal and photo-reduction method. The H 2 evolution rate of optimal photocatalyst 0.5 %Pd modified 5ZnIn 2 S 4 /2P25 (0.5 %Pd@5ZnIn 2 S 4 /2P25) are approximately 9100 and 3693 μmol · g −1 h −1 under simulated sunlight and visible light irradiation with ethanol as the sacrificial agent, which are nearly 9 and 460 times higher than pure ZnIn 2 S 4 and P25, respectively. The promoted photocatalytic performance can be attributed to the physicochemical properties of the catalysts and the strong electronic interaction between Pd modified ZnIn 2 S 4 (Pd@ZnIn 2 S 4 ) and P25, the improved transfer rate of photo-generated electrons and holes, the inhibited recombination of charge carriers, and the enhanced light harvesting. The results of photo-electrochemistry and EPR indicate that it is a Z-scheme photocatalytic system, in which the electrons accumulate on the conduct band of ZnIn 2 S 4 and the holes assemble on the valence band of P25. This work provides an effective method to construct highly efficient photocatalytic systems for solar H 2 generation.
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