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Noble metal
About: Noble metal is a research topic. Over the lifetime, 15113 publications have been published within this topic receiving 337947 citations.
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TL;DR: Comparisons of H2-evolving catalysts in water show that Cat4, although based on a noble metal, is about four times less active, while Cat2 and Cat3 produce more than one hundred times less hydrogen than Cat1.
Abstract: A very efficient homogeneous system for visible-light driven hydrogen production in water is reported. This comprises the [Co(CR)Cl2]+ cobalt(III) tetraaza-macrocyclic complex (Cat1) as a noble metal-free catalyst, [Ru(bpy)3]Cl2 as a photosensitizer and ascorbate/ascorbic acid as a sacrificial electron donor and buffer. This system gives up to 1000 turnovers at pH 4.0 versus the catalyst with a relatively low photosensitizer/catalyst ratio (10/1) and a high concentration of catalyst (1 × 10−4 M), thus producing a significant amount of H2 (12.3 mL for 5 mL of solution). It also exhibits long-term stability (more than 20 hours). The efficiency of Cat1 has been compared under the same experimental conditions to those of three other H2-evolving catalysts, which are known to operate in water, [Co{(DO)(DOH)pn}Br2] (Cat2), [Co(dmbpy)3]Cl2 (Cat3) and [Rh(dmbpy)2Cl2]Cl (Cat4). These comparative studies show that Cat4, although based on a noble metal, is about four times less active, while Cat2 and Cat3 produce more than one hundred times less hydrogen than Cat1. The low-valent CoI form of Cat1 has been successfully electrogenerated in CH3CN. Its high stability can be related to the high catalytic performance of the Cat1 system. We have also shown that in acidic aqueous solution (photocatalytic conditions) reduction at a slightly more negative potential than the CoII/CoI couple is needed to ensure efficient catalysis; this reduction is performed by the photogenerated [RuII(bpy)2(bpy˙−)]+ species.
100 citations
Patent•
21 Oct 2003TL;DR: In this paper, the compositions for reduction of gas phase reduced nitrogen species and NOX generated during a partial or incomplete combustion catalytic cracking process, preferably, a fluid catalytic stripping process, are disclosed.
Abstract: Compositions for reduction of gas phase reduced nitrogen species and NOX generated during a partial or incomplete combustion catalytic cracking process, preferably, a fluid catalytic cracking process, are disclosed. The compositions comprise (i) an acidic metal oxide containing substantially no zeolite, (ii) an alkali metal, alkaline earth metal, and mixtures thereof, (iii) an oxygen storage component, and (iv) a noble metal component, preferably rhodium or iridium, and mixtures thereof, are disclosed. Preferably, the compositions are used as separate additives particles circulated along with the circulating FCC catalyst inventory. Reduced emissions of gas phase reduced nitrogen species and NOX in an effluent off gas of a partial or incomplete combustion FCC regenerator provide for an overall NOX reduction as the effluent gas stream is passed from the FCC regenerator to a CO boiler, whereby as CO is oxidized to CO2 a lesser amount of the reduced nitrogen species is oxidized to NOX.
100 citations
TL;DR: The studies reveal that noble metal doped MOFs are ideal precursors for preparing highly active alloy electrocatalysts with low content of noble metal.
Abstract: The water electrolysis is of critical importance for sustainable hydrogen production. In this work, a highly efficient and stable PdCo alloy catalyst (PdCo@CN) was synthesized by direct annealing of Pd-doped metal–organic frameworks (MOFs) under N2 atmosphere. In 0.5 M H2SO4 solution, PdCo@CN displays remarkable electrocatalytic performance with overpotential of 80 mV, a Tafel slope of 31 mV dec–1, and excellent stability of 10 000 cycles. Our studies reveal that noble metal doped MOFs are ideal precursors for preparing highly active alloy electrocatalysts with low content of noble metal.
100 citations
TL;DR: In this paper, a co-precipitation of M/Mg/Al hydrotalcite-type (HT) anionic clays (M2+/M3+ atomic ratio≈2.5, with the amount of M ranging from 0.04% to 5.0% (as atomic ratio) was successfully prepared by co-preserving in an aqueous solution at pH 10.0, although for the Pt-containing sample about 20% loss of the noble metal ions occurred.
100 citations
TL;DR: The effective photocatalytic H2 evolution under visible light from an Eosin Y (EY)-sensitized (P, Mo)-g-C3Nx system by avoiding any noble metal co-catalyst is reported by the first time.
100 citations