Mechanical properties and geometries of printed products have been extensively studied in metal 3D printing. However, chemical properties and catalytic functions, introduced by metal 3D printing itself, are rarely mentioned. Here we show that metal 3D printing products themselves can simultaneously serve as chemical reactors and catalysts (denoted as selfcatalytic reactor or SCR) for direct conversion of C1 molecules (including CO, CO 2 and CH 4) into high value-added chemicals. The Fe-SCR and Co-SCR successfully catalyze synthesis of liquid fuel from Fischer-Tropsch synthesis and CO 2 hydrogenation; the Ni-SCR efficiently produces syngas (CO/H 2) by CO 2 reforming of CH 4. Further, the Co-SCR geometrical studies indicate that metal 3D printing itself can establish multiple control functions to tune the catalytic product distribution. The present work provides a simple and low-cost manufacturing method to realize functional integration of catalyst and reactor, and will facilitate the developments of chemical synthesis and 3D printing technology.

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Ce promoted Cu/SiO2 catalysts prepared by a urea-assisted gelation approach exhibited excellent catalytic activity and stability for DMO hydrogenation to ethanol.

High quality Al2O3 film grown by atomic layer deposition (ALD), with ozone (O3) as oxygen source, is demonstrated for fabrication of normally-off AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Significant suppression of Al–O–H and Al–Al bonds in ALD-Al2O3 has been realized by substituting conventional H2O source with O3. A high dielectric breakdown E-field of 8.5 MV/cm and good TDDB behavior are achieved in a gate dielectric stack consisting of 13-nm O3-Al2O3 and 2-nm H2O-Al2O3 interfacial layer on recessed GaN. By using this 15-nm gate dielectric and a high-temperature gate-recess technique, the density of positive bulk/interface charges in normally-off AlGaN/GaN MIS-HEMTs is remarkably suppressed to as low as 0.9 × 1012 cm−2, contributing to the realization of normally-off operation with a high threshold voltage of +1.6 V and a low specific ON-resistance RON,sp of 0.49 mΩ cm2.

Low-pressure chemical vapor deposition (LPCVD) technique is utilized for SiN x passivation of AlGaN/GaN high-electron-mobility transistors (HEMTs). A robust SiN x / AlGaN interface featuring high thermal stability and well-ordered crystalline structure is achieved by a processing strategy of "passivation-prior-to-ohmic" in HEMTs fabrication. Effective suppression of surface-trap-induced current collapse and lateral interface leakage current are demonstrated in the LPCVD-SiN x passivated HEMTs, as compared with conventional plasma-enhanced chemical vapor deposition-SiN x passivated ones. Energy dispersive X-ray spectroscopy mapping analysis of SiN x /AlGaN interfaces suggests the interface traps are likely to stem from amorphous oxide/oxynitride interfacial layer. Index Terms-AlGaN/GaN high-electron-mobility transistors (HEMTs), current collapse, low-pressure chemical vapor deposition (LPCVD), oxidation, SiN x passivation.

In this work, Ti/Al/Ni/Au Ohmic contacts to AlGaN/GaN heterostructures with different Ti/Al relative thicknesses were fabricated and characterized. A contact with Ti/Al relative thickness of 20/180 nm presented non-linear current–voltage response and bumpy surface morphology, while a contact with Ti/Al relative thickness of 20/120 nm demonstrated low contact resistance and flat surface morphology. We verify the existence of two electron transport mechanisms, namely carrier tunnelling and direct link through a TiN conductive pathway, by scanning transmission electron microscopy and corresponding electron dispersive x-ray spectra. Ti/Al relative thickness exerts a decisive influence on the alloy reaction processing. Superfluous Al consumes Ti, thus impeding the formation of low-resistance TiN and N vacancies. As a result, electron transport is restricted by the low-efficiency tunnelling mechanism. At the same time, the consumption of Ni causes damage to its blocking effect and arouses the free diffusion of metal alloys, which should be responsible for the rough surface.

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