Ru‐Doping Enhanced Electrocatalysis of Metal–Organic Framework Nanosheets toward Overall Water Splitting

Abstract

An Ru‐doping strategy is reported to substantially improve both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic activity of Ni/Fe‐based metal–organic framework (MOF) for overall water splitting. As‐synthesized Ru‐doped Ni/Fe MIL‐53 MOF nanosheets grown on nickel foam (MIL‐53(Ru‐NiFe)@NF) afford HER and OER current density of 50 mA cm−2 at an overpotential of 62 and 210 mV, respectively, in alkaline solution with a nominal Ru loading of ≈110 μg cm−2. When using as both anodic and cathodic (pre‐)catalyst, MIL‐53(Ru‐NiFe)@NF enables overall water splitting at a current density of 50 mA cm−2 for a cell voltage of 1.6 V without iR compensation, which is much superior to state‐of‐the‐art RuO2‐Pt/C‐based electrolyzer. It is discovered that the Ru‐doping considerably modulates the growth of MOF to form thin nanosheets, and enhances the intrinsic HER electrocatalytic activity by accelerating the sluggish Volmer step and improving the intermediate oxygen adsorption for increased OER catalytic activity.

Acetate promotes the formation of NiRu/NiO towards efficient hydrogen evolution

“…Two more peaks at 464.7 and 486.9 eV are attributed to Ru 3+ 3p 3/2 and Ru 3+ 3p 1/2 , and the generation of Ru 3+ species can be attributed to the surface oxidation. 25 The XPS Ru 3p spectrum of NiRu/Ni(OH) 2 (Fig. S12, ESI †) also verifies the coexistence of metallic Ru and oxidized Ru species.…”

Highly dispersed Ru nanoclusters anchored on B,N co-doped carbon nanotubes for water splitting

“…2d), which are the characteristic peaks attributed to nulvalent Ru. 47 This result suggests that Ru salts have been converted to metallic Ru species. Interestingly, the Ru 3p peaks of the Ru@B,N-CNTs were shifted positively by 0.74 eV when compared to the Ru@B-CNTs and Ru@N-CNTs (Fig.…”

Ru doping boosts electrocatalytic water splitting

“…In addition to the OER, Ru doping is also reported to be effective for optimizing the Gibbs free energy of MOFs to substantially improve the electrocatalytic HER performance. 108 Li et al 109 also realized the regulation of electrocatalytic HER performance of Ni MOFs by a facile Ru single atom doping strategy (Fig. 9d and e).…”