Bias-free solar hydrogen production at 19.8 mA cm-2 using perovskite photocathode and lignocellulosic biomass.

Solar hydrogen production is one of the ultimate technologies needed to realize a carbon-neutral, sustainable society. However, an energy-intensive water oxidation half-reaction together with the poor performance of conventional inorganic photocatalysts have been big hurdles for practical solar hydrogen production. Here we present a photoelectrochemical cell with a record high photocurrent density of 19.8 mA cm-2 for hydrogen production by utilizing a high-performance organic-inorganic halide perovskite as a panchromatic absorber and lignocellulosic biomass as an alternative source of electrons working at lower potentials. In addition, value-added chemicals such as vanillin and acetovanillone are produced via the selective depolymerization of lignin in lignocellulosic biomass while cellulose remains close to intact for further utilization. This study paves the way to improve solar hydrogen productivity and simultaneously realize the effective use of lignocellulosic biomass.

Modular Flow Reactors for Valorization of Kraft Lignin and Low-Voltage Hydrogen Production.

Recent studies have found that green hydrogen production and biomass utilization technologies can be combined to efficiently produce both hydrogen and value-added chemicals using biomass as an electron and proton source. However, the majority of them have been limited to proof-of-concept demonstrations based on batch systems. Here the authors report the design of modular flow systems for the continuous depolymerization and valorization of lignin and low-voltage hydrogen production. A redox-active phosphomolybdic acid is used as a catalyst to depolymerize lignin with the production of aromatic compounds and extraction of electrons for hydrogen production. Individual processes for lignin depolymerization, byproduct separation, and hydrogen production with catalyst reactivation are modularized and integrated to perform the entire process in the serial flow. Consequently, this work enabled a one-flow process from biomass conversion to hydrogen gas generation under a cyclic loop. In addition, the unique advantages of the fluidic system (i.e., effective mass and heat transfer) substantially improved the yield and efficiency, leading to hydrogen production at a higher current density (20.5 mA cm-2 ) at a lower voltage (1.5 V) without oxygen evolution. This sustainable eco-chemical platform envisages scalable co-production of valuable chemicals and green hydrogen for industrial purposes in an energy-saving and safe manner.

Correlation with the Microstructure and Synergistic Physiochemical Etching Resistance of Nanocomposites under Fluorine-Containing Plasma Conditions.

In the semiconductor fabrication industry, high-power plasma is indispensable to obtain a high aspect ratio of chips. For applications to ceramic components including the dielectric window and ring in the semiconductor etching chamber, the Y2O3 ceramics have attracted interest recently based on excellent erosion resistance. When a high bias voltage is applied in a plasma environment containing fluorine gas, both chemical etching and ion bombardment act simultaneously on the ceramic components. During this etching process, severe erosion and particles generated on the ceramic surface can have effects on overall equipment effectiveness. Herein, we report the outstanding plasma etching resistance of Y2O3-MgO nanocomposite ceramics under a CF4/Ar/O2 gas atmosphere; the erosion depth of this material is 40-79% of that of the reference materials, Y2O3 ceramics. In a robust approach involving effective control of the microstructure with different initial particles and sintering conditions, it is possible to understand the relationship between etching behavior and microstructure evolution of the nanocomposite ceramic. The results indicate that the nanocomposite with fine and homogeneous domain distribution can decrease particle generation and ameliorate its life cycle; accordingly, this is a promising alternative candidate material for ceramic components in plasma chambers.

Remarkable plasma-resistance performance by nanocrystalline Y2O3·MgO composite ceramics for semiconductor industry applications.

Motivated by recent finding of crystallographic-orientation-dependent etching behavior of sintered ceramics, the plasma resistance of nanocrystalline Y2O3-MgO composite ceramics (YM) was evaluated for the first time. We report a remarkably high plasma etching resistance of nanostructure YM surpassing the plasma resistance of commercially used transparent Y2O3 and MgAl2O4 ceramics. The pore-free YM ceramic with grain sizes of several hundred nm was fabricated by hot press sintering, enabling theoretical maximum densification at low temperature. The insoluble two components effectively suppressed the grain growth by mutual pinning. The engineering implication of the developed YM nanocomposite imparts enhanced mechanical reliability, better cost effectiveness with excellent plasma resistance property over their counterparts in plasma using semiconductor applications.