Search

Efficient electrocatalytic reactions require a coordinated active center that may provide a properly reaction intermediates adsorption in water splitting. Herein, a Ni active center coordination reconstruction method achieved by multidimensional modulation of phase transition, iodine coordination, and vacancy defects is designed and implemented. This coordination reconstruction results in the successful synthesis of Ni5P4−xIx/Ni2P nanocorals that show outstanding bifunctional catalytic activity due to deep optimization of the adsorption energy. The overpotentials of hydrogen evolution reaction and oxygen evolution reaction at 10 mA cm−2 are 46 and 163 mV, respectively. Only 1.46 V is required to drive alkaline overall water splitting. Novel coordination environment is investigated by electron paramagnetic resonance spectroscopy and extended X‐ray absorption fine structure spectroscopy. A 4D integrated material design strategy of "thermodynamic stability‐electronic properties‐charge transfer‐adsorption energy" for water‐splitting catalysts is proposed. This coordination reconstruction concept and material design method provide new perspectives for the research of novel catalysts. [ABSTRACT FROM AUTHOR]

Direct electrocatalytic oxidation of benzene has been regarded as a promising approach for achieving high‐value phenol product, but remaining a huge challenge. Here an oxygen‐coordinated nickel single‐atom catalyst (Ni–O–C) is reported with bifunctional electrocatalytic activities toward the two‐electron oxygen reduction reaction (2e− ORR) to H2O2 and H2O2‐assisted benzene oxidation to phenol. The Ni–(O–C2)4 sites in Ni–O–C ar proven to be the catalytic active centers for bifunctional 2e− ORR and H2O2‐assisted benzene oxidation processes. As a result, Ni–O–C can afford a benzene conversion as high as 96.4 ± 3.6% with a phenol selectivity of 100% and a Faradaic efficiency (FE) of 80.2 ± 3.2% with the help of H2O2 in 0.1 m KOH electrolyte at 1.5 V (vs RHE). A proof of concept experiment with Ni–O–C concurrently as cathode and anode in a single electrochemical cell demonstrates a benzene conversion of 33.4 ± 2.2% with a phenol selectivity of 100% and a FE of 44.8 ± 3.0% at 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Atomically dispersed Pt species are advocated as a promising electrocatalyst for the oxygen reduction reaction (ORR) to boost noble metal utilization efficiency. However, when assembled on various substrates, isolated Pt single atoms are often demonstrated to proceed through the two‐electron ORR pathway due to the unfavorable O─O bond cleavage thermodynamics in the absence of catalytic ensemble sites. In addition, although their distinct local coordination environments at the exact single active sites are intensively explored, the interactions and synergy between closely neighboring single atom sites remain elusive. Herein, atomically dispersed Pt monomers strongly interacting on a Mo2C support is demonstrated as a model catalyst in the four‐electron ORR, and the beneficial interactions between two closely neighboring and yet non‐contiguous Pt single atom sites (named as quasi‐paired Pt single atoms) are shown. Compared to isolated Pt single atom sites, the quasi‐paired Pt single atoms deliver a superior mass activity of 0.224 A mg−1Pt and near‐100% selectivity toward four‐electron ORR due to the synergistic interaction from the two quasi‐paired Pt atom sites in modulating the binding mode of reaction intermediates. Our first‐principles calculations reveal a unique mechanism of such quasi‐paired configuration for promoting four‐electron ORR. [ABSTRACT FROM AUTHOR]