Bimetallic PdCu Nanocrystals Immobilized by Nitrogen-Containing Ordered Mesoporous Carbon for Electrocatalytic Denitrification

Abstract

Issues of uniform incorporation of catalytic functional species with controllable sizes, shapes, compositions, and functions into porous carbon scaffolds remain significant challenges toward enriching and boosting performance. Here, we develop a straightforward approach that introduces dicyandiamide as a nitrogen source to chelate with metal species and combines with the surfactant-templating selfassembly method for the fabrication of highly dispersed catalysts anchored in nitrogen-containing ordered mesoporous carbon (NOMC). As a result, these functional catalyst (such as PdCu nanocrystals)-embedded NOMC composites manifest a synergistic catalytic capability for the electroreduction of nitrate in neutral electrolyte, with more than 90% nitrate removed under an ultra-low concentration of 100 ppm and a high nitrogen selectivity of 60% after 10 repeated tests.

Precisely Controlled Synthesis of Hybrid Intermetallic–Metal Nanoparticles for Nitrate Electroreduction

“…The high nitrate reduction activity for hybrid Cu 6 Sn 5 –Sn NPs, large current and small onset potential, implies that the RDS is effectively overcome, whereas the reduction reaction stops at the nitrite. This phenomenon is different from noble metal and some reported Cu-based catalysts in the nitrate electroreduction reaction. These catalysts are usually less active (more negative onset potential and low current density) and produce dinitrogen or ammonia as the major products, indicating slow rates on the nitrite formation step but rapid nitrite conversion to the stable N-species.…”

Synergistic Effect of Co(III) and Co(II) in a 3D Structured Co3O4/Carbon Felt Electrode for Enhanced Electrochemical Nitrate Reduction Reaction

“…More importantly, the first step of electrochemically reducing nitrates to nitrites is the rate-determining step for the overall ENRR. , Thus, it is necessary to develop efficient cathodes for improving the rate of nitrate reduction. Owing to its excellent ability of producing atomic hydrogen (H*), platinoid is popularly used as the cathode catalyst in the ENRR such as Pd–Au, PdCu, and Sn–Pd . However, the platinoid suffers from high cost, which limits its application.…”

Tailoring the Assembly of Iron Nanoparticles in Carbon Microspheres toward High-Performance Electrocatalytic Denitrification

“…Energy technology has made great contributions to the progress of scientific and technological research, however, it has also inevitably caused many environmental problems. − Among them, the increasingly serious nitrate contamination in surface and ground waters is a gradual concern because of the risk to human health in drinking water. − Many technologies have been explored for elimination of nitrate from wastewater, including the use of biological and chemical catalysis approaches, but the slow kinetics and high startup costs have limited the further application of these techniques. − Very recently, electrocatalytic nitrate reduction, as an alternative approach, is exposed and well considered to be the most promising method for the effective removal of nitrate because of the environmentally friendly moderate operating conditions and decent efficiency. , In this respect, noble metal and bimetallic nanocrystals have fueled the potential application of electrocatalytic nitrate reduction attributed to the active surface of noble metal and the synergetic effects in the bimetallic system. ,,− This process involves the reaction mechanisms in that electroreduction of nitrate is a stepwise reaction including a “rate-determining step” and a “selectivity-determining step”, leading to the formation of nitrite and the ensuing reduction of intermediate nitrite to N 2 . , However, the widespread applications of noble metal and bimetallic nanocrystals have been severely hindered by several challenges, such as the uncontrolled formation of undesirable ammonia and nitrite as well as the inevitable restriction of high cost . Therefore, exploring some new catalysis to reduce the cost and improve the nitrogen selectivity is of scientific and technological importance.…”