Jie Huang,Jianhang Qiu,Yongqiang Yang,Bing Li,Lianzhou Wang,Hui-Ming Cheng,Gang Liu
Aurivillius compounds-based photocatalysts have attracted extensive interest largely due to their ferroelectric properties and modifiable characteristics arising from the alternate stacking of structural units. However, the interfacial Schottky barrier between such semiconducting compounds as light absorbers and metallic cocatalysts for hydrogen evolution restrains the transfer of photogenerated electrons, resulting in low photocatalytic overall water splitting activity and stability. Here, an anions-induced surface structure transformation strategy is employed to modulate the interface structure between Bi 3 TiNbO 9 as a typical Aurivillius compound and the cocatalyst Rh by in situ growing ultrathin Bi 2 MoO 6 heterolayer on the surface of Bi 3 TiNbO 9 nanosheets. The introduction of Bi 2 MoO 6 heterolayer lowers the energy barrier near the Bi 3 TiNbO 9 surface, which can facilitate the transfer of the photogenerated electrons from bulk to surface and thus the reduction of Rh cocatalyst for highly active hydrogen production. Compared with the Bi 3 TiNbO 9 -Rh photocatalyst, the proportion of low-valence metallic Rh 0 in Bi 2 MoO 6 heterolayer-modified Bi 3 TiNbO 9 -Rh (Bi 3 TiNbO 9 -Bi 2 MoO 6 -Rh) is improved by 7.76%, giving rise to a photocatalytic overall water splitting activity enhancement by a factor of 4.74. This strategy emphasizes the importance of interface regulation in promoting the transfer of photogenerated charge carriers in Aurivillius-type photocatalysts, providing an effective pathway for designing and fabricating high-performance photocatalysts.
Kan Liu,Qifeng Cui,Lu Shi,Jingyu Yang,Yunpeng Cai,Yishi Su,Qiubao Ouyang,Di Zhang
In this work, a novel grain structure tailoring strategy using one-stepped planetary ball milling , different from conventional powder metallurgy routes that pre-prepared components with different microstructures and then mixed them up, was implemented to fabricate micro- and nano-sized SiC particles (m- & n-SiCp)/2024Al composites with heterogeneous lamella structure. The controllable transformation from homogeneous to heterogeneous grain structures is achieved via nonuniformly distributed n-SiCps induced local grain refinement. Heterogeneous lamella composites exhibit a superior modulus-strength-ductility synergy of 95.3 GPa in Young's modulus , 750.7 MPa in tensile strength and 4.9 % in uniform elongation, particularly with no less than 145 % and 175 % improvements in ductility and toughness, compared with homogeneous composites. Compressive stress relaxation experiments were conducted to reveal the structural dependence of plastic deformation behaviors. Sustainedly rising hetero-deformation induced (HDI) stress produced by extra geometrically necessary dislocation (GND) accumulation at heterogeneous soft/hard domain interfaces and sequential activation of multiple dislocation mediated mechanisms based on load transfer in heterogeneous lamella composites contribute to the enhanced strain hardening capacity, which offers intrinsic toughening . Also, extrinsic toughening originates from enhanced microcrack multiplication and crack-tip blunting.
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