Ultratransparent electrodes have attracted considerable attention in optoelectronics and energy technology. However, balancing energy storage capability and transparency remains challenging. Herein, an in situ strategy employing a temporally and spatially shaped femtosecond laser is reported for photochemically synthesizing of MXene quantum dots (MQDs) uniformly attached to laser reduced graphene oxide (LRGO) with exceptional electrochemical capacitance and ultrahigh transparency. The mechanism and plasma dynamics of the synthesis process are analyzed and observed at the same time. The unique MQDs loaded on LRGO greatly improve the specific surface area of the electrode due to the nanoscale size and additional edge states. The MQD/LRGO supercapacitor has high flexibility and durability, ultrahigh energy density (2.04 × 10−3 mWh cm−2), long cycle life (97.6% after 12 000 cycles), and excellent capacitance (10.42 mF cm−2) with both high transparency (transmittance over 90%) and high performance. Furthermore, this method provides a means of preparing nanostructured composite electrode materials and exploiting quantum capacitance effects for energy storage.

Epitaxial MnSi1.7 was grown locally on both (111) and (001)Si. The orientation relationships were found to be [11̄0]MnSi1.7//[111]Si, (220)MnSi1.7//(22̄0)Si and [001]MnSi1.7//[001]Si, (100)MnSi1.7//(400)Si for epitaxy grown on (111) and (001)Si samples, respectively. Three variants of epitaxy, required by the symmetry consideration, were also observed to form on (111)Si. Interfacial dislocations were identified to be of edge type with (1)/(6) 〈112〉 and 1/2 〈110〉 Burgers vectors for epitaxial MnSi1.7 grown on (111) and (001)Si, respectively. The presence of different forms of MnSi1.7 is suggested in view of the important difference in details of diffraction patterns of MnSi1.7 along the [001] direction. The growth of epitaxial MnSi1.7 on silicon has filled the ‘‘gap’’ of the growth of stable phases of silicides of the fourth period transition elements in the periodic table epitaxially on silicon.

Nonlinear optical properties have been extensively studied due to their promising nonlinear effects and various applications. With ultrashort duration and ultrahigh intensity, a femtosecond laser can fabricate various superior-quality micro-/ nanostructures to improve the nonlinearity of materials, which are promising for stable and high-performance nonlinear devices. In this contribution, yttria-stabilized zirconia (YSZ) with fs laser-induced micro-/nanostructures is demonstrated to exhibit unique anisotropic light−material interaction and nonlinear optical response on [100], [110], and [111] planes. Time-resolved reflectivity of YSZ after fs laser excitation is investigated by a pump−probe experiment, which is consistent with simulations through the plasma model combined with a two-temperature model. These results indicate two early ablation mechanisms: Coulomb explosion and melting. Anisotropic crack structures are formed due to thermal stress, which is always ignored in fs laser fabrication and is verified by Raman mapping and analysis of slip systems on different crystal planes. Through the z-scan measurement, the nonlinear absorption (NLA) of crack structures is effectively improved, and a nearly 18 times enhancement of the NLA coefficient is acquired in [100] samples, while a 2 times enhancement in [110] and [111] samples. Such great enhancement of NLA is mainly due to the abundant presence of crack structures and the increase of fs laser-induced oxygen vacancies in [100] YSZ. These results provide a potential way of utilizing fs laser to improve the nonlinearity for the technological development in nonlinear devices.

No abstract