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Mushrooms can be found in forests worldwide and have long been exploited as resources in developed economies because of their important agro-industrial, medicinal and commercial uses. For less developed countries, such as those within the Greater Mekong Subregion, wild harvesting and mushroom cultivation provides a much-needed alternative source of income for rural households. However, this has led to over-harvesting and ultimately environmental degradation in certain areas, thus management guidelines allowing for a more sustained approach to the use of wild mushrooms is required. This article addresses a selection of the most popular and highly sought after edible mushrooms from Greater Mekong Subregion: Astraeus hygrometricus, Boletus edulis, Morchella conica, Ophiocordyceps sinensis, Phlebopus portentosus, Pleurotus giganteus, Termitomyces eurhizus, Thelephora ganbajun, Tricholoma matsuake, and Tuber indicum in terms of value, ecology and conservation. The greatest threat to these and many other mushroom species is that of habitat loss and over-harvesting of wild stocks, thus, by creating awareness of these issues we wish to enable a more sustainable use of these natural products. Thus our paper provides baseline data for these fungi so that future monitoring can establish the effects of continued harvesting on mushroom populations and the related host species.

Intermetallic electrides have recently shown their priority as catalyst components in ammonia synthesis and CO2 activation. However, their function mechanism has been elusive since its inception, which hinders the further development of such catalysts. In this work, ternary intermetallic electrides La–TM–Si (TM = Co, Fe, and Mn) were synthesized as hosts of ruthenium (Ru) particles for ammonia synthesis catalysis. Although they have the same crystal structure and possess low work functions commonly, the promotion effects on Ru particles rather differ from each other. The catalytic activity follows the sequence of Ru/LaCoSi > Ru/LaFeSi > Ru/LaMnSi. Furthermore, Ru/LaCoSi exhibits much better catalytic durability than the other two. A combination of experiments and first-principles calculations shows that apparent N2 activation energy on each catalyst is much lower than that over conventional Ru-based catalysts, which suggests that N2 dissociation can be conspicuously promoted by the concerted actions of the specific electronic structure and atomic configuration of intermetallic electride-supported catalysts. The NH x formations proceeded on La are energetically favored, which makes it possible to bypass the scaling relations based on only Ru as the active site. The rate-determining step of Ru/La–TM–Si was identified to be NH2 formation. The transition metal (TM) in La–TM–Si electrides has a significant influence on the metal–support interaction of Ru and La–TM–Si. These findings provide a guide for the development of new and effective catalyst hosts for ammonia synthesis and other hydrogenation reactions.

Electrides have shown their significant advantages in NH 3 synthesis as catalysts or supports under mild conditions. A better understanding of the unconventional reaction kinetics of electrides can greatly promote the development of this kind of novel catalyst. However, most electride-based catalysts are supported ones whose complexity hampers the mechanism study. In this article, the essence behind the catalytic performance of a LaRuSi electride was uncovered using a combination of experiments and first-principles calculations. The LaRuSi electride was found to be capable of disrupting the scaling relations via two mechanisms, which ensured high catalytic performance for NH 3 synthesis. First, a very low N 2 activation energy on a Ru-terminated surface can be achieved without extremely strong adsorption of nitrogen species; then, a second efficient active site (La site) for NH x formation further significantly reduces the barriers for the overall reaction. A comparative study with CaRuSi, a nonelectride but with the same structure, reveals that the catalytic effect of LaRuSi is indeed derived from the characteristics of anionic electrons. This study delivers insights into the working mechanism of electride-based catalysts and can stimulate the design of new catalytic materials with improved performance.

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