Effective Ensemble of Pt Single Atoms and Clusters over the (Ni,Co)(OH)₂ Substrate Catalyzes Highly Selective, Efficient, and Stable Hydrogenation Reactions

Abstract

A Pt−Ni−Co catalyst was synthesized with Pt single atoms and atomic clusters (SAACs) dispersed over (Ni,Co)(OH) 2 nanoparticles on a carbon matrix, which leads to high catalytic activity, up to 100% conversion, and selectivity in the hydrogenation of nitroaromatics under moderate conditions (H 2 ∼ 1.0 MPa and ≤40 °C). A synergistically coordinated ensemble effect of the Pt SAACs is identified with the strongly polarized Pt single atoms preferentially adsorbing the −NO 2 and the Pt clusters adsorbing and homolytically dissociating H 2 molecules, and the H species then readily move to the adsorbed −NO 2 group, overcoming a much reduced energy barrier on the (Ni,Co)(OH) 2 , enhancing the reaction rate by ca. 50 times. The approach not only reveals the coordinated ensemble catalysis mechanism of SAACs but also provides a strategy of developing highly efficient and selective catalysts by fine tuning of the electronic microenvironment from single atoms to atomic clusters co-located over a multimetallic substrate. The demonstrated case for nitroarenes can be readily applied for other species containing −NO 2 or other easily hydrogenated groups (such as CC, CN, and CO).

Effective electronic tuning of Pt single atomsviaheterogeneous atomic coordination of (Co,Ni)(OH)2for efficient hydrogen evolution

“…In our recent study, a finelytuned electronic microenvironment of Pt single atoms and clusters co-located over a (Ni,Co)(OH) 2 substrate effectively reduced the energy barrier for hydrogen transfer on (Ni,Co)(OH) 2 to enhance hydrogenation reactions. [55][56][57][58] With the above, we resorted to engineering Pt single atoms and their local environments on defective (Co,Ni)(OH) 2 , Co(OH) 2 , and Ni(OH) 2 by a facile electrodeposition strategy (see the Methods section for details in the ESI †). The optimized Pt 1 /(Co,Ni)(OH) 2 /C nanostructure, with Pt single atoms embedded in [(Co,Ni)(OH) 2 ] nanoparticles (termed Pt 1 /(Co,Ni)(OH) 2 ) delivered exceptionally high catalytic activity, even with only 1.41 wt% Pt loading.…”

“…In our recent study, a finely-tuned electronic microenvironment of Pt single atoms and clusters co-located over a (Ni,Co)(OH) 2 substrate effectively reduced the energy barrier for hydrogen transfer on the (Ni,Co)(OH) 2 , to enhance hydrogenation reactions. [55][56][57][58] With the above, we resorted to engineering Pt single atoms and their local environments on defective (Co,Ni)(OH) 2 , Co(OH) /C exhibited far superior HER activity (24 mV@10 mA•cm -2 with a Tafel slope of 28.7 mV dec -1 ) to Pt 1 /Co(OH) 2 /C (50 mV@10 mA•cm -2 , 48.7 mVdec -1 ), Pt 1 /Ni(OH) 2 /C (55 mV@10 mA•cm -2 , 52.1 mV dec -1 ) and the commercial 20 wt% Pt/C (29 mV@10 mA cm -2 , 32.5 mV dec -1 ) in 1.0 M KOH solution. Especially, Pt 1 /(Co,Ni)(OH) 2 /C showed an ultralow overpotential and an outstanding electrocatalytic mass activity for the HER, which was 29.7 times over Pt 1 /C and 115.9 times higher than that of the commercial 20 wt% Pt/C at 0.09 V vs. RHE, respectively.…”

“…In our recent study, a finely-tuned electronic microenvironment of Pt single atoms and clusters co-located over a (Ni,Co)(OH) 2 substrate effectively reduced the energy barrier for hydrogen transfer on (Ni,Co)(OH) 2 to enhance hydrogenation reactions. 55–58…”

Nickel Hydroxide‐Supported Ru Single Atoms and Pd Nanoclusters for Enhanced Electrocatalytic Hydrogen Evolution and Ethanol Oxidation

“…In view of previous works in our group on the regulation of precious metals and hydroxides, [36,37] the rational combination of Pd, Ru, and transition metal hydroxides species may provide a promising strategy for the design of advanced functional electrocatalysts with outstanding activity and favorable toxicity resistance. Herein, we report a universal method for the rational design of Pd x Ru y /Ni(OH) 2 /C with different Pd/Ru ratios (x:y is the atomic ratio) with Pd nanoclusters, Ru single atoms anchored at the defective sites of Ni(OH) 2 for accelerating HER and EOR reactivity in alkaline medium.…”

Electrostatic Spinning Strategy to Prepare Cage-like PAN-Fiber Network-Wrapped Co–N–C Structures for the Oxygen Reduction Reaction

“…Co 2p can be divided into three pairs of peaks in Figure f. The binding energies of 778.22 and 792.91 eV correspond to Co (0), while the binding energies at 785.93 and 801.67 eV correspond to satellite peaks. ,− The binding energy of Co-N-C@PAN at 780.09 and 796.73 eV correspond to the Co-Nx bond as shown in Figure S2a, and the Co–N X percentage content of 55.1% for Co–N–C@PAN yield to be the most which compared with Co–N–C (50.31%) in Table S1. The presence of Co–N X is favorable for the electrocatalysis of the ORR, indicating that the addition of PAN leads to an increase in Co–N X , which promotes the catalysis of the ORR.…”