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"Precious metals."
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Strong precious metal–metal oxide interaction for oxygen reduction reaction: A strategy for efficient catalyst design
Oxygen reduction reaction (ORR) is an electrochemical reaction in which dissolved oxygen in an electrolyte is reduced to OH−/H2O when receiving electrons. This reaction plays a crucial role in shaping the efficiency of both metal–air batteries and fuel cells, and precious metals are the dominant catalysts carrying out the ORR in their cathodes. However, how to manipulate the electronic structure of precious metals as active sites to further promote ORR performance and maximize the utilization rate is still under development. Metal oxide serves as suitable and promising support that can strongly interact with precious metals for both activity and durability enhancement. Herein, we present recent research updates on strong precious metal–metal oxide interaction (SPMMOI) utilized in ORR. We start by introducing the background of ORR, the issues to be solved, and its practical applications followed by a thorough discussion of the reaction mechanism and comprehensive evaluation protocols of performance. We then provide a complete understanding of the working principle of SPMMOI and highlight the related advances. Finally, we summarize the merits of the precious metal–metal oxide system and propose the research direction as well as some urgent problems to be addressed in the future. Recent advances and future perspectives in heterogeneous electrocatalyst design for oxygen reduction reaction (ORR) based on strong metal–support interaction (SMSI) mechanism were demonstrated in this review.
Journal Article
Statistical analyses of precious metal contents in waste incineration bottom ashes
The recovery of precious metals from incinerator bottom ash (IBA) is a way of moving towards a circular economy. The paper presents a detailed analysis of the concentration of precious metals in IBA. The average values of precious metals in the samples analyzed are: Ag—6973 ppb, Au—313.90 ppb, Pd—41.26 ppb, Pt—13.81 ppb—all of these values being many times higher than the values of these elements in the Earth’s crust. The time series of the precious metals in the IBA were analyzed to assess the trend, seasonality, and outliers and to detect differences between the designated seasons of the year. Data analysis was performed following the CRISP-DM methodology using statistical and data mining methods. The analyzes confirmed a higher Ag concentration than in comparable European waste incinerator plants. The Au concentration was comparable to those reported in other incinerators, while the values were lower for Pt and Pd. The time series of precious metals shows no trend and seasonality, but numerous outliers. Due to the stationarity of precious metals, recovery can be expected to be constant, and the presence of numerous outliers can increase the potential return on investment.
Journal Article
Gem : the definitive visual guide
\"Feast your eyes on glittering gemstones, kaleidoscopic minerals, and famous trinkets in this comprehensive exploration of Earth's finest jewels. Following a foreword from Aja Raden, hundreds of pages take a lavish look at precious stones, precious metals, and organic gems in all their natural wonder. From agate to zoisite, everything under the Sun is encapsulated in spectacular photography and accessible text. Discover the intriguing stories of the world's most famous and fabulous gems, including the mysterious Hope Diamond, the stunning Koh-i-Noor of the Crown Jewels, and exquisite Fabergé eggs. Trace the history of gemmology, learn all about the key characteristics of precious and semi-precious stones, and discover the science behind some of their more unusual and mysterious properties\"-- Provided by publisher.
BOOK
Recovery of rare and precious metals from urban mines —— A review
Urban mining is essential for continued natural resource extraction. The recovery of rare and precious metals （RPMs） from urban mines has attracted increasing attention from both academic and industrial sectors, because of the broad application and high price of RPMs, and their low content in natural ores. This study summarizes the distribution characteristics of various RPMs in urban mines, and the advantages and shortcomings of various technologies for RPM recovery from urban mines, including both conventional （pyrometallurgical, hydrometallurgical, and biometallurgical processing）, and emerging （electrochemical, supereritieal fluid, mechanochemical, and ionic liquids processing） technologies. Mechanical/physical technologies are commonly employed to separate RPMs from nonmetallic components in a pre-treatment process. A pyrometallurgical process is often used tbr RPM recovery, although the expensive equipment required has limited its use in small and medium-sized enterprises. Hydrometallurgical processing is effective and easy to operate, with high selectivity of target metals and high recovery efficiency of RPMs, compared to pyrometallurgy. Biometallurgy, though, has shown the most promise for leaching RPMs from urban mines, because of its low cost and environmental friendliness. Newly developed technologies electrochemical, supercritical fluid, ionic liquid, and mechanochemical have offered new choices and achieved some success in laboratory experiments, especially as efficient and environmentally friendly methods of recycling RPMs. With continuing advances in science and technology, more technologies will no doubt be developed in this field, and be able to contribute to the sustainability of RPM mining.
Journal Article
Silver
\"Silver has always been a precious metal, used in photography, dentistry, currency, knives, forks, and spoons (better known as, yes, silverware!). Silver is used in x-rays, mirrors, and even medical bandages. In this book, we'll explore how silver was first discovered and used, and how it forms into compounds and alloys. Readers will discover where silver fits in the Periodic Table, and how silver plays a part in modern day electronics from cell phones to computers, but is no longer used in coins, given its expense. Interesting chemistry terms are accompanied by illustrations and photographs to bring silver to gleaming life.\"-- Provided by publisher.
Book
Hybrid neural network-based metaheuristics for prediction of financial markets: a case study on global gold market
Abstract
Technical analysis indicators are popular tools in financial markets. These tools help investors to identify buy and sell signals with relatively large errors. The main goal of this study is to develop new practical methods to identify fake signals obtained from technical analysis indicators in the precious metals market. In this paper, we analyze these indicators in different ways based on the recorded signals for 10 months. The main novelty of this research is to propose hybrid neural network-based metaheuristic algorithms for analyzing them accurately while increasing the performance of the signals obtained from technical analysis indicators. We combine a convolutional neural network and a bidirectional gated recurrent unit whose hyperparameters are optimized using the firefly metaheuristic algorithm. To determine and select the most influential variables on the target variable, we use another successful recently developed metaheuristic, namely, the moth-flame optimization algorithm. Finally, we compare the performance of the proposed models with other state-of-the-art single and hybrid deep learning and machine learning methods from the literature. Finally, the main finding is that the proposed neural network-based metaheuristics can be useful as a decision support tool for investors to address and control the enormous uncertainties in the financial and precious metals markets.
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Graphical Abstract
Journal Article
Titanium
Explains the characteristics of titanium, where it is found, how it is mined, and some of its uses, including ship hulls, durable tools, and pigments.
Book
Research Progress on Porous Carbon-Based Non-Precious Metal Electrocatalysts
The development of efficient, stable, and economic electrocatalysts are key to the large-scale application of electrochemical energy conversion. Porous carbon-based non-precious metal electrocatalysts are considered to be the most promising materials to replace Pt-based catalysts, which are limited in large-scale applications due to high costs. Because of its high specific surface area and easily regulated structure, a porous carbon matrix is conducive to the dispersion of active sites and mass transfer, showing great potential in electrocatalysis. This review will focus on porous carbon-based non-precious metal electrocatalysts and summarize their new progress, focusing on the synthesis and design of porous carbon matrix, metal-free carbon-based catalysts, non-previous metal monatomic carbon-based catalyst, and non-precious metal nanoparticle carbon-based catalysts. In addition, current challenges and future trends will be discussed for better development of porous carbon-based non-precious metal electrocatalysts.
Journal Article