Rational Design of Ruthenium and Cobalt-Based Composites with Rich Metal–Insulator Interfaces for Efficient and Stable Overall Water Splitting in Acidic Electrolyte

Abstract

The great promise of hydrogen energy and hydrogen production from water through proton exchange membrane (PEM) or membrane-free electrolysis drives the pursuit of highly active and acid-stable electrocatalysts with dual functionality and reduced cost for overall water splitting in acidic media. Here, we report a new Ru-modified cobalt-based electrocatalyst embedded in a nitrogen-doped carbon (NC) matrix with rationally designed Mott−Schottky heterostructure to realize high activity and stability toward overall water splitting in a strongly acidic environment. Such a composite was facilely prepared by carbonization of cobalt-based MOF, followed by galvanic exchange between cobalt and Ru, and then controlled partial oxidation. The partial oxidation of RuCo implanted inside the NC matrix led to the formation of a class of RuO 2 / Co 3 O 4 −RuCo@NC composites with rich metal−semiconductor interfaces to facilitate the charge-transfer process. As a result, the composite displayed remarkable electrocatalytic activity toward both oxygen/hydrogen evolutions in acidic media. Significantly, they also afforded low overpotentials of 247 and 141 mV for OER and HER, respectively, and a cell voltage of 1.66 V for overall water splitting at 10 mA cm −2 . In addition, excellent operation stability in 0.5 M H 2 SO 4 solutions, comparable to those of them working in alkaline conditions, is demonstrated due to the protection of a coated carbon thin film. The presented work opens a new opportunity toward designing bifunctional electrocatalysts for acidic water electrolysis.

Designing MOF Nanoarchitectures for Electrochemical Water Splitting

“…A recently reported Ru-modified Co-based electrocatalyst, which was anchored in an N-doped carbon (NC) matrix and presented a rationally designed Mott−Schottky heterostructure (RuO 2 /Co 3 O 4 -RuCo@NC), achieved outstanding activity and stability for overall water splitting under strongly acidic conditions. [121] RuO 2 /Co 3 O 4 -RuCo@ NC was synthesized via a three-step process: pyrolysis of Co-MOF, galvanic replacement reaction between Co and Ru, and controlled partial oxidation. Notably, the composite with rich metal-semiconductor interfaces obtained by partial oxidation could promote the charge-transfer process; thus, the catalytic performance would be further improved.…”

“…In recent times, a versatile strategy for designing highperformance electrocatalysts has been to controllably introduce two different metal species into a single nanostructure, namely Co-NC@ Mo 2 C, [119] Co 3 O 4 -RuCo@NC, [121] NG-NiFe@MoC 2 , [256] Co/Co 9 S 8 @ NSOC, [122] NiO/Co 3 O 4 , [120] Co@Ir/NC, [257] Ni 2 P/CoN-PCP, [258] among others, [92,[259][260][261][262][263][264] to further facilitate and accelerate the activation process of the reactants. For instance, Hu et al synthesized MoC 2 -doped NiFe alloy nanoparticles (NPs) embedded within several-layer-thick N-doped graphene (NG-NiFe@MoC 2 ) using one-step calcination of hybrid precursors composed of PVP-encapsulating NiFe-PBA and grafted Mo 6+ cations (Figure 15Ba).…”

Nanostructured RuO2–Co3O4@RuCo-EO with low Ru loading as a high-efficiency electrochemical oxygen evolution catalyst

“…36,38,40 At the same time, related literature has also proven that the rich metal-insulator interface structure is benecial to improve the OER activity of Ru. 37,39 Therefore, it is hoped that both the Mott-Schottky effect will improve the charge transfer rate and the alloying will also optimize the electronic structure of Ru. This paper pays more attention to the preparation of the RuCo alloy base and the construction of the special surface morphology in the research method.…”

Hydrogen Evolution Reaction - From Single Crystal to Single Atom Catalysts

“…Other works focused on preparation of HER active chalcogenides and hydroxides include Ni-Co sulfide/Ni-Co carbonate-hydroxide grown on Ni foam [95], MoS2@Ni(OH)2/Ni foam [96], Co9S8@MoS2 [97], Te@NiTe2/NiS [98], MoS2 coated Ni3S2 [99], WS2 supported on TiO2 [100], N-doped reduced graphene oxide supported CoSe2 [101], Co9S8 supported on N,S co-doped carbon [102], MoNiS@NiS [103], Mo-incorporated Ni(OH)2 [104], Ni2P-NiSe2 [105], NiCo2S4/CdO [106], Ni3S2 decorated by Ni3Sn2S2 quantum dots [107], metallic WSe2:Sn supported on reduced graphene oxide [108], and RuO2/Co3O4-RuCo supported on N-doped carbon [109].…”