Continuous Modulation of Electrocatalytic Oxygen Reduction Activities of Single‐Atom Catalysts throughp‐nJunction Rectification

Abstract

Fine-tuning single-atom catalysts (SACs) to surpass their activity limit remains challenging at their atomic scale. Herein, we exploit p-type semiconducting character of SACs having a metal center coordinated to nitrogen donors (MeN x ) and rectify their local charge density by an n-type semiconductor support. With iron phthalocyanine (FePc) as a model SAC, introducing an n-type gallium monosulfide that features a low work function generates a space-charged region across the junction interface, and causes distortion of the FeN 4 moiety and spin-state transition in the Fe II center. This catalyst shows an over two-fold higher specific oxygen-reduction activity than that of pristine FePc. We further employ three other n-type metal chalcogenides of varying work function as supports, and discover a linear correlation between the activities of the supported FeN 4 and the rectification degrees, which clearly indicates that SACs can be continuously tuned by this rectification strategy.

A high-entropy atomic environment converts inactive to active sites for electrocatalysis

“…Among the many factors affecting the activity, selectivity, and stability of heterogeneous catalysts, the adsorption behavior of reactants/ intermediates/products at the active sites of the catalyst surface plays a very important role. [26][27][28][29][30][31] The unique advantage of HEAs is that there are many kinds of metal sites in nanoparticles (NPs), and the main explanation for the ultrahigh activity and stability of HEA electrocatalysts is the synergistic effect of multiple metal sites. 32,33 The coexistence of multiple competing adsorption sites often leads to unsatisfactory reaction selectivity.…”

Enhancing Heterogeneous Catalysis by Electronic Property Regulation of Single Atom Catalysts

“…The introduction of Ptn crowded the α-MoC surface thus contributed to eliminating excess surface oxygen species and further improved its stability. Besides, they found the unique CO activation and successive reforming pathway ( 13 C 16 O *' + *' → 13 C *' + 16 O *' , 2 13 C *' + 2 18 OH *' → 2 13 C 18 O + H2 + 2 * + 2 *' , 13 C *' + 2 18 OH *' → 13 C 18 O2 + H2 + 2 * + 2 *' ) to produce additional hydrogen by transient kinetic analysis using 13 C 16 O and H2 18 O as feeds (Fig. 9d).…”

“…However, different from the early development stage of SACs, it becomes harder for researchers to elevate the catalytic performance of SACs through aimless trials. In order to move further, researchers start to focus on the synergetic catalysts (like dual-atom site catalysts [8][9][10][11][12][13] , single atoms plus NPs 14 ), physical picture 15,16 and the electronic properties of the catalysts 17,18 . Among these, the underlying electronic states of active sites (i.e., supported single metal atoms) need to be comprehensively investigated because they are the direct adsorption sites for reactants and intermediates, the subtle change in microenvironment of which could exert an influence on the internal reactivity 16,19 .…”

“…In order to move further, researchers start to focus on the synergetic catalysts (like dual-atom site catalysts [8][9][10][11][12][13] , single atoms plus NPs 14 ), physical picture 15,16 and the electronic properties of the catalysts 17,18 . Among these, the underlying electronic states of active sites (i.e., supported single metal atoms) need to be comprehensively investigated because they are the direct adsorption sites for reactants and intermediates, the subtle change in microenvironment of which could exert an influence on the internal reactivity 16,19 . Since the insight into electronic properties could guide the rational construction of SACs and also help to understand the reaction mechanism, we are in urgent need of the thorough comprehension of electronic metal-support interaction (EMSI) together with the structureactivity correlations 20 .…”

Ultrafine Core@Shell Cu1Au1@Cu1Pd3 Nanodots Synergized with 3D Porous N-Doped Graphene Nanosheets as a High-Performance Multifunctional Electrocatalyst

“…Pt is widely accepted as the most effective polycrystalline single metal for catalyzing the ORR; however, the scarce resource and the resulting high price have severely hindered its large-scale application in LTFCs. ,− Fortunately, Pd shows an ORR electrocatalytic activity comparable with that of Pt in alkaline media and also has a much higher abundance in the Earth’s crust, , which make it a promising alternative. Moreover, plenty of studies have demonstrated that Pd is much more active for the electro-oxidation of alcohols than Pt in alkaline media. , Thus, Pd-based nanomaterials have become a very appealing material platform for designing and preparing high-performance electrocatalysts used for alkaline DAFCs.…”