Trifunctional Single‐Atomic Ru Sites Enable Efficient Overall Water Splitting and Oxygen Reduction in Acidic Media

Abstract

Energy crisis and environmental pollution trigger the development of efficient and robust electrochemical energy conversion and storage technologies. [1-3] The electrocatalytic reactions, such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), undoubtedly play key roles in developing renewable energy conversion devices, Development of cost-effective, active trifunctional catalysts for acidic oxygen reduction (ORR) as well as hydrogen and oxygen evolution reactions (HER and OER, respectively) is highly desirable, albeit challenging. Herein, singleatomic Ru sites anchored onto Ti 3 C 2 T x MXene nanosheets are first reported to serve as trifunctional electrocatalysts for simultaneously catalyzing acidic HER, OER, and ORR. A half-wave potential of 0.80 V for ORR and small overpotentials of 290 and 70 mV for OER and HER, respectively, at 10 mA cm −2 are achieved. Hence, a low cell voltage of 1.56 V is required for the acidic overall water splitting. The maximum power density of an H 2-O 2 fuel cell using the as-prepared catalyst can reach as high as 941 mW cm −2. Theoretical calculations reveal that isolated Ru-O 2 sites can effectively optimize the adsorption of reactants/intermediates and lower the energy barriers for the potentialdetermining steps, thereby accelerating the HER, ORR, and OER kinetics.

Three-dimensional hierarchical Co(OH)F nanosheet arrays decorated by single-atom Ru for boosting oxygen evolution reaction

“…For the curve of SA-Ru/Co(OH)F, a main peak appearing at 1.61 Å results [17]. No peaks assigned to Ru-Ru bonds (2.41 Å) are observed, effectively indicating that Ru exists in a form of single atom [42]. After OER testing, the Ru-O peak negatively shifts to 1.58 Å but is still stronger than that of RuO 2 , implying that Ru oxidation state is lower than +4.…”

Engineering Ruthenium-Based Electrocatalysts for Effective Hydrogen Evolution Reaction

“…In [88], with permission from the American Chemical Society [91,92], MOF [93], Graphdiyne [94], MXene [95,96], and nitrogen-doped carbon [97].…”

MXenes as Superexcellent Support for Confining Single Atom: Properties, Synthesis, and Electrocatalytic Applications

“…The Lately, Liu and co-workers confined single atomic Ru site onto MXene support (Ru SA/Ti 3 C 2 T X ) by coordinating O termination for efficient electrochemical OWS in acidic media. [106] The Gibbs free energy of intermediate hydrogen adsorption for Ti 3 C 2 T X was 0.13 eV, and the value was decreased to 0.11 eV after infusing single atom Ru, which was closed to Pt(111) (0.09 eV) (Figure 7a). The result revealed that Ru SA/ Ti 3 C 2 T X was energetically biased to H adsorption-desorption to facilitate H 2 generation, thereby enhancing HER activity.…”

“…Reproduced with permission. [106] Copyright 2020, Wiley-VCH. and low-cost electrocatalyst is essential.…”