Photoelectrochemical (PEC) reduction of carbon dioxide (CO ) is a potential method for production of fuels and chemicals from a C1 feedstock accumulated in the atmosphere. However, the low solubility of CO in water, and complicated processes associated with capture and conversion, render CO conversion inefficient. A new concept is proposed in which a PEC system is used to capture and convert CO into formic acid. The process is assisted by an ionic liquid (1-aminopropyl-3-methylimidazolium bromide) aqueous solution, which functions as an absorbent and electrolyte at ambient temperature and pressure. Within this PEC reduction strategy, the ionic liquid plays a critical role in promoting the conversion of CO to formic acid and suppressing the reduction of H O to H . At an applied voltage of 1.7 V, the Faradaic efficiency for formic acid production is as high as 94.1 % and the electro-to-chemical efficiency is 86.2 %.

In this work, we demonstrate that a graphene oxide (GO) hydrogel with unique rheological properties, such as high storage modulus, shear-thinning nature and fast viscosity recovery, is highly suitable as an ink for three dimensional (3D) printing. The results show that the GO ink has the characteristics of both gel and viscous liquid, where the gel-liquid transition depends on the shear rate and shear strain amplitude. In the extrusion and printing process, the ink shows significant shear thinning and rapid viscosity recovery after cessation of shearing, which are desirable for 3D printing through direct ink writing (DIW). A suitable scanning speed and extrusion speed were determined to construct a precise 3D structure. After the reduction, the RGO electrode with hierarchical porous structures is stable, of higher precision, and loaded with more of the effective materials per unit area. The 3D printed micro-supercapacitors (MSCs) with interdigitated architecture exhibit a high areal specific capacitance of 101 mF cm À2 at a current density of 0.5 mA cm À2 and 111 mF cm À2 at a scan rate of 10 mV s À1 , which are superior compared with most of the reported MSCs of carbon-based materials. Fig. 1 (a) Schematic illustration of the fabrication process of 3DHG-MSCs, (b) structural decomposition diagram of 3DHG-MSCs, (c) optical image of the 3D interdigitated architecture composed of three-pair fingers with 5 printed layers, (d) optical microscopic image of 3DHG electrode.This journal is

Silicon (Si) nanomembranes (NMs) enable conformal covering on complicated surfaces for novel applications. We adopt classical fibers as flexible/curved substrates and wrap them with freestanding ultrathin Si-NMs with a thickness of ∼20 nm. Intrinsic defects in single-crystalline Si-NMs provide a flow path for hydrofluoric acid (HF) to release the NM with a consecutive area of ∼0.25 cm. Such Si-NMs with ultralow flexural rigidities are transferred onto a single-mode fiber (SMF) and functionalized into bendable photodetectors, which detects the leaked light when the fiber is bent. Our demonstration exemplifies optoelectronic applications in flexible photodetector for Si-NMs in a three-dimensional (3D) geometry.

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