Pd–PdO Nanodomains on Amorphous Ru Metallene Oxide for High‐Performance Multifunctional Electrocatalysis

Abstract

renewable electricity into hydrogen fuel, while the latter plays an indispensable role in eco-friendly fuel cells and metalair batteries. [2] However, the fundamental electrode reactions that lie at the heart of these technologies, including the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER), are inherently slow. Thus, high-performance electrocatalysts are inevitably required to accelerate the reaction kinetics, enhance the Faradaic efficiency, and minimize the Ohmic losses. Extensive research has revealed numerous electrocatalysts that drive these critical reactions. One such group of electrocatalysts-Platinum group metals (PGMs)-based materialsis extensively recognized for their optimal functionality, close-to-zero overpotentials, and excellent intrinsic activities. [3] Nevertheless, the high cost associated with using the resource-scarce PGMs significantly hinders the large-scale implementation of the technologies. [4] Therefore, it is crucial to improve the efficiency of PGM-based electrocatalysts via optimizing the intrinsic activity, maximizing atomic utilization, and enhancing operational stability. Furthermore, developing an electrocatalyst with multifunctionality is highly desirable to Developing highly efficient multifunctional electrocatalysts is crucial for future sustainable energy pursuits, but remains a great challenge. Herein, a facile synthetic strategy is used to confine atomically thin Pd-PdO nanodomains to amorphous Ru metallene oxide (RuO 2 ). The as-synthesized electrocatalyst (Pd 2 RuOx-0.5 h) exhibits excellent catalytic activity toward the pH-universal hydrogen evolution reaction (η 10 = 14 mV in 1 m KOH, η 10 = 12 mV in 0.5 m H 2 SO 4 , and η 10 = 22 mV in 1 m PBS), alkaline oxygen evolution reaction (η 10 = 225 mV), and overall water splitting (E 10 = 1.49 V) with high mass activity and operational stability. Further reduction endows the material (Pd 2 RuOx-2 h) with a promising alkaline oxygen reduction activity, evidenced by high halfway potential, four-electron selectivity, and excellent poison tolerance. The enhanced catalytic activity is attributed to the rational integration of favorable nanostructures, including 1) the atomically thin nanosheet morphology, 2) the coexisting amorphous and defective crystalline phases, and 3) the multi-component heterostructural features. These structural factors effectively regulate the material's electronic configuration and the adsorption of intermediates at the active sites for favorable reaction energetics.

Activating Amorphous Ru Metallenes Through Co Integration for Enhanced Water Electrolysis

“…Additionally, it is also highly desirable for electrocatalysts to manifest bifunctionality which could directly reduce the fabrication and operational cost. [ 24,25 ]…”

“…Additionally, it is also highly desirable for electrocatalysts to manifest bifunctionality which could directly reduce the fabrication and operational cost. [24,25] Metallenes, demonstrating an ultrathin 2D graphene-like structure saturated with undercoordinated metal atoms, have recently attracted substantial interest in electrocatalysis as well as diverse other applications, such as sensing, photothermal therapy, and solar cells. [26,27] In contrast to their bulk counterparts, metallenes present unique physicochemical properties including excellent electron conductivity, surface reactivity due to atomic undercoordination, highly active surface area, and tunable electronic properties which render them highly desirable, particularly, for surface-sensitive electrocatalysis.…”

“…[37,38] Moreover, disrupting the long-range geometrical symmetry as induced by amorphization can additionally result in unsaturated sites and abundant defects oriented in a randomized fashion, exerting profound influences on the underlying catalytic activity compared to their crystalline counterparts. [24,39,40] For example, amorphous Co(OH) 2 nanosheets (NSs), compared to crystalline Co(OH) 2 , were found to exhibit superior OER activity attributed to the increased availability of active sites resulting from the disordered atomic arrangement. [41] However, most of the state-of-the-art metallenes developed to date possess rich crystallinity.…”

Order–disorder engineering of RuO2nanosheets towards pH-universal oxygen evolution

“…Moreover, the amorphous regions provide structural flexibility to the Ru-based catalysts, which results in greater tolerance to structural disturbances, thereby contributing to a reduced dissolution rate of Ru sites and a better stability relative to the crystalline phase. [30][31][32][33] However, amorphous structures suffer from sluggish kinetics of electron transfer between the Ru sites and the oxygen-containing adsorbates due to low electrical conductivity, which undesirably counteracts much of the further enhancement of the OER performance. [34][35][36][37] In view of this, considering the separate advantages of amorphous and crystalline phases, the design of Ru-based OER catalysts with amorphous-crystalline phases can be expected to achieve both high activity and durability.…”

Oxygen-Bridged Stabilization of Single Atomic W on Rh Metallenes for Robust and Efficient pH-Universal Hydrogen Evolution

“…Electrochemical water splitting presents a sustainable and environmentally benign pathway for the generation of molecular hydrogen, a clean energy carrier, via leveraging on Earth-abundant water and renewable power as feedstocks. Undoubtedly, the derivation of practical and efficient water electrolyzer technology, capable of large-scale hydrogen production, is expected to hold prospective contributions to the hydrogen economy as well as to global energy security. − Nevertheless, this approach fundamentally hinges on the development of high-performance electrocatalysts for driving the cathodic hydrogen evolution reaction (HER). , Thus far, platinum (Pt) marks the gold standard element for HER, on account of its fast reaction kinetics and near-optimal binding strength with hydrogen. − Unfortunately, the high cost associated with the precious metal, activity deterioration owing to Ostwald ripening and coalescence behaviors of Pt nanoparticles (NPs), susceptibility to leaching in corrosive electrolytes and suboptimum water dissociation kinetics in alkaline and neutral electrolytes, raises immediate and ineluctable concerns on the viability of Pt-based electrocatalysts. − On this note, electrocatalysts, as alternatives to Pt, endowed with excellent catalytic activity, durability and functionality for HER across a wide pH range are of paramount importance, yet extremely challenging. − …”