Raw biomass electroreforming coupled to green hydrogen generation

Despite the tremendous progress of coupling organic electrooxidation with hydrogen generation in a hybrid electrolysis, electroreforming of raw biomass coupled to green hydrogen generation has not been reported yet due to the rigid polymeric structures of raw biomass. Herein, we electrooxidize the most abundant natural amino biopolymer chitin to acetate with over 90% yield in hybrid electrolysis. The overall energy consumption of electrolysis can be reduced by 15% due to the thermodynamically and kinetically more favorable chitin oxidation over water oxidation. In obvious contrast to small organics as the anodic reactant, the abundance of chitin endows the new oxidation reaction excellent scalability. A solar-driven electroreforming of chitin and chitin-containing shrimp shell waste is coupled to safe green hydrogen production thanks to the liquid anodic product and suppression of oxygen evolution. Our work thus demonstrates a scalable and safe process for resource upcycling and green hydrogen production for a sustainable energy future.

The scale-up of the coupling of water electroreduction (HER) with organic electrooxidation remains challenging. Here the authors address this challenge by coupling HER with electrooxidation of raw biomass chitin, cogenerating acetate and green hydrogen safely at high current density.

Lignocellulose, Cellulose and Lignin as Renewable Alternative Fuels for Direct Biomass Fuel Cells

In recent years the use of renewable sources, such as lignocellulosic biomass (LCB), as the fuel for various types of fuel cells received growing interest. Different types of fuel cells, that is, operated at low temperatures (T<100 °C; microbial fuel cells (MFC), alkaline (AFCs) and flow fuel cells (FFCs)), intermediate temperatures (T in the range 150-300 °C, proton-conducting inorganic-organic composite membrane fuel cells), and high temperatures (T≥500 °C, direct carbon fuel cells (DCFCs)), have been used for the conversion of the chemical energy in LCB to electrical energy. The economic advantage of the direct use of LCB consists of avoiding the acid hydrolysis of cellulose to glucose for low-temperature fuel cells and the pretreatment at high temperatures necessary to convert biomass to biochar (pyrolysis) in the case of high-temperature fuel cells. In this Review, the characteristics of direct biomass fuel cells are presented and their performance is compared with that of indirect biomass fuel cells fed with glucose (low-temperature fuel cells) and biochar (high-temperature fuel cells).

Hydrogen production from cellulose catalyzed by an iridium complex in ionic liquid under mild conditions

A new and simple method for hydrogen production from cellulose using an iridium catalyst and an ionic liquid under mild conditions was developed.

Recent advances in the electrooxidation of biomass-based organic molecules for energy, chemicals and hydrogen production

The recent developments in biomass-derivative fuelled electrochemical converters for electricity or hydrogen production together with chemical electrosynthesis have been reviewed.

Intermediate-temperature electrolysis of energy grass Miscanthus sinensis for sustainable hydrogen production

Biohydrogen produced from the electrolysis of biomass is promising because the onset voltages are less than 1.0 V and comparable to those of water and alcohol-water electrolysis. The present study focuses on Miscanthus sinensis as a model grass because of its abundance and ease of cultivation in Japan. The electrochemical performance and hydrogen formation properties of electrolysis cells using grass as a biohydrogen source were evaluated at intermediate temperature to achieve electrolysis. The components, such as holocellulose, cellulose, lignin, and extractives, were separated from Miscanthus sinensis to understand the reactions of Miscanthus sinensis in the electrolysis cell. The relatively high resistivity and low current-voltage performance of an electrolysis cell using lignin were responsible for degradation of the electrolysis properties compared to those with pure cellulose or holocellulose as biohydrogen resources. Biohydrogen was formed according to Faraday’s law and evolved continuously at 0.1 A cm⁻² for 3,000 seconds.

The W alloying effect on thermal stability and hardening of nanostructured Cu-W alloyed thin films

In order to achieve desired mechanical properties of alloys by manipulating grain boundaries (GBs) via solute decoration, it is of great significance to understand the underlying mechanisms of microstructural evolution and plastic deformation. In this work, nanocrystalline (NC) Cu-W alloyed films with W concentrations spanning from 0 to 40 at% were prepared by using magnetron sputtering. Thermal stability (within the temperature range of 200 °C-600 °C) and hardness of the films were investigated by using the x-ray diffraction, transmission electron microscope (TEM) and nanoindentation, respectively. The NC pure Cu film exhibited substantial grain growth upon all annealing temperatures. The Cu-W alloyed films, however, displayed distinct microstructural evolution that depended not only on the W concentration but also on the annealing temperature. At a low temperature of 200 °C, all the Cu-W alloyed films were highly stable, with unconspicuous change in grain sizes. At high temperatures of 400 °C and 600 °C, the microstructural evolution was greatly controlled by the W concentrations. The Cu-W films with low W concentration manifested abnormal grain growth (AGG), while the ones with high W concentrations showed phase separation. TEM observations unveiled that the AGG in the Cu-W alloyed thin films was rationalized by GB migration. Nanoindentation results showed that, although the hardness of both the as-deposited and annealed Cu-W alloyed thin films monotonically increased with W concentrations, a transition from annealing hardening to annealing softening was interestingly observed at the critical W addition of ∼25 at%. It was further revealed that an enhanced GB segregation associated with detwinning was responsible for the annealing hardening, while a reduced solid solution hardening for the annealing softening.