Hydrogen production from electrochemical water splitting is a promising route to pursue clean and sustainable energy sources. Here, a three-dimensional nanoporous Cu−Ru alloy is prepared as a high-performance platinum-free catalyst for hydrogen evolution reaction (HER) by a dealloying process. Significantly, the optimized nanoporous alloy Cu 53 Ru 47 exhibits remarkable catalytic activity for HER with nearly zero onset overpotential and ultralow Tafel slopes (∼30 and ∼35 mV dec −1 ) in both alkaline and neutral electrolytes, achieving a catalytic current density of 10 mA cm −2 at low overpotentials of ∼15 and ∼41 mV, respectively. Operando Xray absorption spectroscopy experiments, in conjunction with DFT simulations, reveal that the incorporation of Ru atoms into the Cu matrix not only accelerates the reaction step rates of water adsorption and activation but also optimizes the hydrogen bonding energy on Cu and Ru active sites, improving the intrinsic activity for HER.
Although significant progresses have been achieved recently in developing catalysts for electrochemical oxygen evolution in alkaline electrolytes, high performance catalysts toward oxygen evolution in acidic media have not been realized in spite of the technical importance for the development of promising energy transformation technologies including electrocatalytic water splitting, integrated (photo)electrochemistry cells, rechargeable metal-air batteries, and so on. Here, we synthesized a three-dimensional nanoporous Ir 70 Ni 30-x Co x alloy microwires as oxygen evolution reaction electrocatalyst using a dealloying strategy. The three dimensional binderfree np-Ir 70 Ni 15 Co 15 catalyst in 0.1 M HClO 4 shows a low overpotential (220 mV@ η = 10 mA cm −2), low Tafel slope (44.1 mV dec −1) and excellent corrosion resistance, significantly outperforming commercial IrO 2 catalysts. The excellent performance is attributed to the nanoporous structure and the alloying effect, which promote the permeation of electrolyte, accelerate the transportation of electrons. More importantly, the high valence Ir oxide species with low-coordination structure in np-Ir 70 Ni 15 Co 15 alloy are identified for the real catalytic sites of OER process by the XAS results acquired on synchrotron radiation. This work not only provides fundamental understandings of the correlation between surface activity and stability for OER catalysts, but also paves a new way to advanced electrocatalysts working in acidic media.
The design of highly active and stable catalysts for the oxygen evolution reaction (OER) in acidic media has become an attractive research area for the development of energy conversion and storage technologies. However, progress in this area has been limited by the poor understanding of the dynamic active structure of catalysts under realistic OER conditions. Here, an atomic Co-doped nanoporous RuO 2 electrocatalyst, which exhibited excellent OER activity and stability in acidic conditions, was synthesized through annealing and etching of a nanoporous Co-Ru alloy. Operando X-ray absorption spectroscopy results confirmed that the etching strategy produced abundant oxygen vacancies around the metal centers in the atomic Co-doped nanoporous RuO 2 electrocatalyst. These vacancies created contracted metaloxygen ligand bonds under realistic OER conditions. The dynamic structural evolution of the synthesized electrocatalyst allowed them to experience lower kinetic barriers during OER catalysis, resulting in enhanced catalytic activity and stability. This study also provided atomic details on the active structure of the electrocatalyst and the influence of their structural evolution on OER activity.
Electrochemical synthesis of carbamoylphosphonates via P–H phosphorylation and oxygenation of phosphinecarboxamides with alcohols by using n-Bu4NI (10 mol%) as an iodine source.
A one-step, I 2 -promoted PÀH phosphorylation and oxygenation of phosphinecarboxamides to give carbamoylphosphonates was achieved. This transformation exhibits exceptional substrate generality and functional group compatibility and affords good to excellent yields of the desired phosphonates. Notably, cyclic carbamoylphosphonates can be obtained from diols. The mechanism was investigated using IR, 1 H and 31 P NMR spectroscopy.
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