Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

Abstract

Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

Atomically Dispersed Mo Supported on Metallic Co9S8 Nanoflakes as an Advanced Noble‐Metal‐Free Bifunctional Water Splitting Catalyst Working in Universal pH Conditions

“…Energy Mater. [7] Meanwhile, the curve (insets of Figure 3f) illustrates almost steady current density of ≈10 mA cm −2 for a 72 h chronoamperometry running in 1.0 m KOH solution. a,d) LSV and b,e) Tafel curves for OER of Mo-Co 9 S 8 @C and the controlled samples in 0.5 m H 2 SO 4 and 1.0 m KOH with a scan rate of 5 mV s −1 at room temperature, respectively.…”

“…Furthermore, the current−time curve (insets of Figure 3c) also indicates that Mo-Co 9 S 8 @C reserves similar catalytic performance for at least 24 h in 0.5 m H 2 SO 4 . [7,12,24] Such superior electrocatalytic activity of Mo-Co 9 S 8 @C might be attributed to the following merits: 1) the synergetic interactions between high oxidation state Co and single-atomic Mo species to form insoluble compounds under acidic conditions, which benefits the OER and overall water splitting in different pH conditions; 2) our working electrode is directly in situ grown on the carbon cloth, which also contributes to the enhancement of long-time stability. Energy Mater.…”

“…[8] Moreover, RuO 2 usually suffers from a rapid deactivation. [7,10] However, those cost-effective catalysts usually suffer from large onset potentials, high overpotential and poor stability especially at high current densities. Only a few non-noble metal catalysts (such as Co 3 O 4 , MnO x , Co-POMs, NiFeP, N-doped WC, MoSe 2 NS/MoO 2 NB/CNT-M, and Co-doped MoS 2 ) have been reported that functionalized in an acidic media.…”

Plasma‐Triggered Synergy of Exfoliation, Phase Transformation, and Surface Engineering in Cobalt Diselenide for Enhanced Water Oxidation

“…[1] Hydrogen, with ahigh energy density, is regarded as an attractive candidate. [5] Therefore,i ti su rgent to explore more economical alternatives with equivalent or better activity and stability based on earth-abundant elements for achieving sustainable water electrolysis technology.Tr ansition-metal (M = Fe,C o, Ni)d ichalcogenides (X 2 = S 2 ,Se 2 ,T e 2 )have been recently attractive for promoting OER electrocatalysis owing to their intriguing structural and electronic properties. [3] To date,n oble-metal oxides,s uch as RuO 2 and IrO 2 ,r emain the workhorse catalysts to accelerate the process.…”

“…[3] To date,n oble-metal oxides,s uch as RuO 2 and IrO 2 ,r emain the workhorse catalysts to accelerate the process. [5] Therefore,i ti su rgent to explore more economical alternatives with equivalent or better activity and stability based on earth-abundant elements for achieving sustainable water electrolysis technology. [5] Therefore,i ti su rgent to explore more economical alternatives with equivalent or better activity and stability based on earth-abundant elements for achieving sustainable water electrolysis technology.…”