In situ TEM Characterization of Microstructure Evolution and Mechanical Behavior of the 3D-Printed Inconel 718 Exposed to High Temperature

This in situ transmission electron microscopy work presents a nanoscale characterization of the microstructural evolution in 3D-printed Inconel 718 (IN718) while exposed to elevated temperature and an associated change in the mechanical property under tensile loading. Here, we utilized a specially designed specimen shape that enables tensile testing of nano-sized thin films without off-plane deformations. Additionally, it allows a seamless transition from the in situ heating to tensile experiment using the same specimen, which enables a direct correlation of the microstructure and the mechanical property of the sample. The method was successfully used to observe the residual stress relaxation and the formation of incoherent γ′ precipitates when temperature was increased to 700°C. The subsequent in situ tensile test revealed that the exposure of the as-printed IN718 to a high temperature without full heat treatment (solutionizing and double aging) leads to loss of ductility

Designing the Electrochemical Interface to Enable Lithium Metal Batteries

Although Li-ion battery is one of the most widely used energy storage devices, there have been extensive efforts to push its limit to meet the ever-increasing demands to improve its energy density for applications such as electric vehicles, portable electronics, and grid storages. Here, Li metal anode plays a key role in the next generation energy storage devices, ultimately enabling the anode-free configuration. However, there are major challenges that need to be overcome for a successful deployment of anode-free batteries. These include designing a competitive SEI, low Coulombic efficiency, and the formation of dendrites. To realize an effective anode-free configuration modifying the copper collector, adding a 3D host and tuning the electrolyte of the key. In this work, we adopted gallium-based liquid metal (LM) as a coating layer on a copper current collector to uniformly deposit Li and prevent the dendrite formation to improve the cycle performance. The effect of the LM coating was confirmed by in situ transmission electron microscopy and optical microscopy observations. LM reduced the charge/discharge overpotentials with its high affinity with Li. It also contributed to decompose the dendritic Li in the discharge process reducing the dead Li disconnected from the current collector. The LM coating was further fortified by graphene oxide (GO) overlayer to prevent the direct contact of electrolyte with uniformly deposited Li. The GO overlayer acted as a barrier and as a 3D host for the deposited Li. Furthermore, we combined in situ TEM and first principles calculations to investigate the electrochemical stability of the solid electrolyte and the structural evolution in contact with Li to study a potential direction to mitigate Li dendrites and enable Li metal anode

Periodically Ordered Nanoporous Perovskite Photoelectrode For Efficient Photoelectrochemical Water Splitting

Nonmetallic materials with localized surface plasmon resonance (LSPR) have a great potential for solar energy harvesting applications. Exploring nonmetallic plasmonic materials is desirable yet challenging. Herein, an efficient nonmetallic plasmonic perovskite photoelectrode, namely, SrTiO3, with a periodically ordered nanoporous structure showing an intense LSPR in the visible light region is reported. The crystalline-core@amorphous-shell structure of the SrTiO3 photoelectrode enables a strong LSPR due to the high charge carrier density induced by oxygen vacancies in the amorphous shell. The reversible tunability in LSPR of the SrTiO3 photoelectrode was observed by oxidation/reduction treatment and incident angle adjusting. Such a nonmetallic plasmonic SrTiO3 photoelectrode displays a dramatic plasmon-enhanced photoelectrochemical water splitting performance with a photocurrent density of 170.0 μA cm-2 under visible light illumination and a maximum incident photon-to-current-conversion efficiency of 4.0% in the visible light region, which are comparable to the state-of-the-art plasmonic noble metal sensitized photoelectrodes

Drastic Enhancement Of Photoelectrochemical Water Splitting Performance Over Plasmonic Al@Tio2 Heterostructured Nanocavity Arrays

Herein, we presented nonprecious plasmonic Al@TiO2 heterostructures for efficient photoelectrochemical (PEC) water splitting by controllably isolating Aluminum (Al) nanoparticles (NPs) individually into TiO2 nanocavity arrays (NCAs). Compared with bare TiO2, the Al@TiO2 shows the most prominently enhanced PEC performance under solar light illumination. The significantly enhanced PEC activity of Al@TiO2 photoanode is attributed to the localized surface plasmonic resonance (LSPR) induced electromagnetic field enhancement in UV–visible region and photoinduced hot carrier of Al NPs. Moreover, the naturally formed Al2O3 ultrathin layer can act as a protective layer by restraining Al NPs corrosion and reducing the surface charge recombination. This study reveals that a novel plasmonic system can be rationalized by forming isolated earth-abundant metal into the nanostructured semiconductor film with a highly ordered morphology, which opens a new paradigm for advanced catalyst design for PEC water splitting

In Situ Transmission Electron Microscopy: A Powerful Tool For The Characterization Of Carrier-Selective Contacts

The goal of this paper is to provide an overview of an in situ transmission electron microscopy (TEM) technique used to study the thermal stability of various transition metal oxide-based contacts used as carrier-selective contacts in silicon solar cells. In the present work, MoOx/Al and WOx/Al were investigated as hole-selective rear contacts using a combination of in situ TEM and transmission line measurements (TLM)

Thermal Stability Of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study

In this study, the thermal stability of a contact structure featuring hole-selective tungsten oxide (WOx) and aluminum deposited onto p-type crystalline silicon (c-Si/WOx/Al) was investigated using a combination of transmission line measurements (TLM) and in situ transmission electron microscopy (TEM) studies. The TEM images provide insight into why the charge carrier transport and recombination characteristics change as a function of temperature, particularly as the samples are annealed at temperatures above 500 °C. In the as-deposited state, a ≈ 2 nm silicon oxide (SiOx) interlayer forms at the c-Si/WOx interface and a ≈ 2–3 nm aluminum oxide (AlOx) interlayer at the WOx/Al interface. When annealing above 500 °C, Al diffusion begins, and above 600 °C complete intermixing of the SiOx, WOx, AlOx and Al layers occurs. This results in a large drop in the contact resistivity, but is the likely reason surface recombination increases at these high temperatures, since a c-Si/Al contact is basically being formed. This work provides some fundamental insight that can help in the development of WOx films as hole-selective rear contacts for p-type solar cells. Furthermore, this study demonstrates that in situ TEM can provide valuable information about thermal stability of transition metal oxides functioning as carrier-selective contacts in silicon solar cells

In Situ Transmission Electron Microscopy Study Of Molybdenum Oxide Contacts For Silicon Solar Cells

In this study, a molybdenum oxide (MoO x ) and aluminum (Al) contact structure for crystalline silicon (c-Si) solar cells is investigated using a combination of transmission line measurements (TLM) and in-situ transmission electron microscopy (TEM). Cross-sectional high-resolution TEM (HRTEM) micrographs reveal a ≈2 nm silicon oxide (SiO x ) interlayer at c-Si/MoO x interface in the as-deposited state, indicating that formation of SiO x occurs during deposition of MoO x . Moreover, oxygen diffusion takes place from MoO x toward Al resulting in the formation of a ≈2–3 nm aluminum oxide (AlO x ) interlayer at the MoO x /Al interface. Overall, it is observed that MoO x /Al contact is relatively stable upon annealing up to 200 °C and still retains ohmic transport with sufficiently low contact resistivity

Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study.

In this study, the thermal stability of a contact structure featuring hole-selective tungsten oxide (WOx) and aluminum deposited onto p-type crystalline silicon (c-Si/WOx/Al) was investigated using a combination of transmission line measurements (TLM) and in situ transmission electron microscopy (TEM) studies. The TEM images provide insight into why the charge carrier transport and recombination characteristics change as a function of temperature, particularly as the samples are annealed at temperatures above 500 °C. In the as-deposited state, a ≈ 2 nm silicon oxide (SiOx) interlayer forms at the c-Si/WOx interface and a ≈ 2-3 nm aluminum oxide (AlOx) interlayer at the WOx/Al interface. When annealing above 500 °C, Al diffusion begins, and above 600 °C complete intermixing of the SiOx, WOx, AlOx and Al layers occurs. This results in a large drop in the contact resistivity, but is the likely reason surface recombination increases at these high temperatures, since a c-Si/Al contact is basically being formed. This work provides some fundamental insight that can help in the development of WOx films as hole-selective rear contacts for p-type solar cells. Furthermore, this study demonstrates that in situ TEM can provide valuable information about thermal stability of transition metal oxides functioning as carrier-selective contacts in silicon solar cells

Periodically Ordered Nanoporous Perovskite Photoelectrode for Efficient Photoelectrochemical Water Splitting

Nonmetallic materials with localized surface plasmon resonance (LSPR) have a great potential for solar energy harvesting applications. Exploring nonmetallic plasmonic materials is desirable yet challenging. Herein, an efficient nonmetallic plasmonic perovskite photoelectrode, namely, SrTiO₃, with a periodically ordered nanoporous structure showing an intense LSPR in the visible light region is reported. The crystalline-core@amorphous-shell structure of the SrTiO₃ photoelectrode enables a strong LSPR due to the high charge carrier density induced by oxygen vacancies in the amorphous shell. The reversible tunability in LSPR of the SrTiO₃ photoelectrode was observed by oxidation/reduction treatment and incident angle adjusting. Such a nonmetallic plasmonic SrTiO₃ photoelectrode displays a dramatic plasmon-enhanced photoelectrochemical water splitting performance with a photocurrent density of 170.0 μA cm^–2 under visible light illumination and a maximum incident photon-to-current-conversion efficiency of 4.0% in the visible light region, which are comparable to the state-of-the-art plasmonic noble metal sensitized photoelectrodes