Electrochemical hydrolytic hydrogen production is the most promising method for renewable energy storage and conversion. However, the kinetic slow oxygen evolution reaction (OER) limits the development of water electrolysis at the anode. The state-of-the-art OER catalysts face a dilemma of high content of noble metals and low OER activities. Herein, a strategy for achieving efficient and stable high-entropy alloy (HEA) catalysts by Mo-coordination is reported. The earth-abundant FeCoNiMo HEA catalyst provides an overpotential as low as 250 mV at the current density of 10 mA cm −2 in alkaline medium, which is 89 mV lower than that of state-of-the-art IrO 2 . The turnover frequency of 0.051 s −1 at the overpotential of 300 mV of FeCoNiMo HEA is 3 times higher than that of commercial IrO 2 catalyst and even 11 times higher than that of the FeCoNi alloy without Mo-coordination. Importantly, the FeCoNiMo HEA exhibits high OER stability at a high current density of 100 mA cm −2 . Methanol molecular probe experiment and X-ray photoelectron spectroscopy analyses suggest that the electrons of Mo transfer to Fe, Co, and Ni in the FeCoNiMo HEA catalyst, which leads to a weakened OH* bonding and, as a result, enhanced OER performance of the FeCoNiMo HEA catalyst. Consistent with the methanol molecular probe analysis, the real-time OER kinetic simulation reveals that the coordination of Mo within FeCoNi can speed up the rate-determining OH* deprotonation step of OER. Our finding opens up a routine for designing efficient cost-effective electrocatalysts for OER, which could facilitate discoveries in OER catalysts.

Although the metal-organic framework (MOF) based materials have become one of the most important types of electrocatalysts for the sluggish oxygen evolution reaction (OER), a novel design strategy for the MOF structure is highly needed to overcome the current development bottleneck of the electrochemical performance. Reconstructing MOFs towards a designed framework structure provides breakthrough opportunities to achieve unprecedented OER electrocatalytic performance, but has rarely, if ever, been proposed and investigated yet due to the signi cant challenges during the synthesis. Here, we report the rst successful fabrication of a robust OER electrocatalyst by precision reconstruction of an MOF structure from MOF-74-Fe to MIL-53(Fe)-2OH with different coordination environments at the active sites.Theoretical calculations have revealed that the Fe sites in MIL-53(Fe)-2OH with uncoordinated phenolic hydroxyls are more electroactive than that in MOF-74-Fe. Bene ting from this desired electronic structure, the designed MIL-53(Fe)-2OH catalyst exhibits unprecedentedly high intrinsic OER activity, including a low overpotential of 215 mV at 10 mA cm−2, low Tafel slope of 45.4 mV dec−1 and high turnover frequency (TOF) of 1.44 s−1 at the overpotential of 300 mV, which is 81 times higher than the TOF of the commercial IrO2 catalyst (0.0177 s−1). The radically reduced eg-t2g crystal eld splitting in Fe-3d and thus the much suppressed electron hopping barriers through the synergistic effects of the O species from the coordinated carboxyl groups and the uncoordinated phenolic groups guarantee the e cient OER in MIL-53(Fe)-2OH. Consistent with the DFT calculations, the real-time kinetic simulation reveals that the conversion from O* to OOH* is the rate-determining step on the active sites of MIL-53(Fe)-2OH. This work establishes a MOF platform to systematically investigate the structure-property relationship for rationally designing and fabricating robust OER electrocatalysts in the future.

Electrochemical oxygen reduction for producing clean hydrogen peroxide (H2O2) is a promising alternative approach to the industrial anthraquinone method. At present, the most pressing challenge is the development of oxygen reduction electrocatalysts with sufficient activity, stability, and 2e− pathway selectivity. Here, the electrocatalytic properties of a series of graphitic carbon nitride (g‐C3N4) catalysts with different concentrations of nitrogen species (CNC and N(C)3) are explored for H2O2 production. Electrochemical studies show that the selectivity of g‐C3N4 for hydrogen peroxide generation in alkaline electrolytes reaches ≈90%. To explain the observed results, the structure, composition, and physical and chemical properties of g‐C3N4 catalysts synthesized from different precursors are compared with their electrocatalytic performance. This research contributes to the discovery and design of a high‐performance nitrogen‐doped carbon catalysts for the production of hydrogen peroxide.

A novel two-dimensional Co-MOF material {[Co(dptz)2(oba)2]·(DMF)2}n is prepared by using mixed organic ligands, which exhibits both OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) catalytic performance. The integration of...

No abstract