Cation‐Vacancy‐Enriched Nickel Phosphide for Efficient Electrosynthesis of Hydrogen Peroxides

Abstract

highly dependent on the adsorption model of oxygen molecules (O 2 ) on the surface of catalysts. [2] The side-on adsorption with a "*O-O*" configuration (* presents the active site) is conducive to weakening the O-O bond for reduction of O 2 into H 2 O via a four-electron (4e) ORR pathway, [3] while the end-on configuration formed by a solo oxygen atom coordinated on a single active site ("*OOH" intermediate) facilitates to selectively catalyzing oxygen to generate H 2 O 2 via a two-electron (2e) ORR pathway. [4] To realize 2e oxygen electroreduction, various strategies including alloying, [5] chemical functionalization, [6] downsizing, [7] and single-atom engineering [8] have been developed to regulate the physicochemical properties of the catalysts. Though substantial progress has been made, the activity and durability of reported works still cannot compete with the demand of the practical application. [9] The cation vacancy engineering strategy could be an effective approach to develop high-performance catalysts for the electrocatalytic synthesis of H 2 O 2 owing to the following merits: creating cation vacancy on host materials can prolong the distance or spacing of the active sites, thereby leading to the formation of *OOH adsorption favorable; [4a] the charge density between active sites and adjacent coordination atoms will be redistributed, which optimizes the Electrocatalytic hydrogen peroxide (H 2 O 2 ) synthesis via the two-electron oxygen reduction reaction (2e ORR) pathway is becoming increasingly important due to the green production process. Here, cationic vacancies on nickel phosphide, as a proof-of-concept to regulate the catalyst's physicochemical properties, are introduced for efficient H 2 O 2 electrosynthesis. The as-fabricated Ni cationic vacancies (V Ni )-enriched Ni 2−x P-V Ni electrocatalyst exhibits remarkable 2e ORR performance with H 2 O 2 molar fraction of >95% and Faradaic efficiencies of >90% in all pH conditions under a wide range of applied potentials. Impressively, the as-created V Ni possesses superb longterm durability for over 50 h, suppassing all the recently reported catalysts for H 2 O 2 electrosynthesis. Operando X-ray absorption near-edge spectroscopy (XANES) and synchrotron Fourier transform infrared (SR-FTIR) combining theoretical calculations reveal that the excellent catalytic performance originates from the V Ni -induced geometric and electronic structural optimization, thus promoting oxygen adsorption to the 2e ORR favored "end-on" configuration. It is believed that the demonstrated cation vacancy engineering is an effective strategy toward creating active heterogeneous catalysts with atomic precision.

Composition Engineering of Amorphous Nickel Boride Nanoarchitectures Enabling Highly Efficient Electrosynthesis of Hydrogen Peroxide

“…Recently, several kinds of inexpensive transition metalbased compounds including oxides, [15][16][17] chalcogenides, [18][19][20] and phosphides [21][22][23] have been exploited for selective reduction of O 2 to H 2 O 2 , by which their huge potential as 2e − ORR electrocatalysts has been eloquently confirmed. For instance, in 2021, Jiang et al found that the Cu 7.2 Se 4 delivered the 2e − selectivity as high as 90%, [18] and following this observation, Zhao et al in 2022 reported that the 2e − selectivity for Ni 2−x P could be reached higher than 92%.…”

“…For instance, in 2021, Jiang et al found that the Cu 7.2 Se 4 delivered the 2e − selectivity as high as 90%, [18] and following this observation, Zhao et al in 2022 reported that the 2e − selectivity for Ni 2−x P could be reached higher than 92%. [21] To further enhance the selectivity, very recently, Menezes and his coworkers synthesized the high entropy perovskite oxides, which displayed a 2e − selectivity up to 96%. [24] Not only these remarkable new findings are appealing but also they are inspiring others to search for more diverse transition metal-based (TM) electrocatalysts toward 2e − ORR.…”

Synergetic Dual‐Ion Centers Boosting Metal Organic Framework Alloy Catalysts toward Efficient Two Electron Oxygen Reduction

“…Hydrogen peroxide (H 2 O 2 ) is an important commodity chemical and has versatile applications in the fields of wastewater incorporation, [24] crystallinity modification, [25] and ions confinement, [17] have been used to regulate 3d electron structure of active metal Ni sites for manipulating the adsorption energetics of *OOH intermediates toward an efficient 2e -ORR process. Moreover, bimetallic MOFs with similar 3d electronic configurations have been demonstrated to exhibit promising catalytic activity toward oxygen evolution, because of the optimized adsorption energetics of crucial intermediates over the synergetic transition metal cations.…”

3D Fe3O4-decorated Nitrogen-doped Graphene Aerogel as a Highly Durable Electrocatalyst for Oxygen Reduction Reactions

“…ORR is a complicated multielectron transfer process with various reaction pathways (2eand 4e -). Therefore, the rational design of electrocatalysts is the key to achieving superior activity, high selectivity, and excellent durability [3]. Platinum-based catalysts exhibit excellent catalytic activity towards 4e -ORR, but the high cost, poor stability, and methanol resistance of such catalysts make it necessary to explore alternative candidates [4].…”