A membrane-free flow electrolyzer operating at high current density using earth-abundant catalysts for water splitting

Abstract

Electrochemical water splitting is one of the most sustainable approaches for generating hydrogen. Because of the inherent constraints associated with the architecture and materials, the conventional alkaline water electrolyzer and the emerging proton exchange membrane electrolyzer are suffering from low efficiency and high materials/operation costs, respectively. Herein, we design a membrane-free flow electrolyzer, featuring a sandwich-like architecture and a cyclic operation mode, for decoupled overall water splitting. Comprised of two physically-separated compartments with flowing H2-rich catholyte and O2-rich anolyte, the cell delivers H2 with a purity >99.1%. Its low internal ohmic resistance, highly active yet affordable bifunctional catalysts and efficient mass transport enable the water splitting at current density of 750 mA cm−2 biased at 2.1 V. The eletrolyzer works equally well both in deionized water and in regular tap water. This work demonstrates the opportunity of combining the advantages of different electrolyzer concepts for water splitting via cell architecture and materials design, opening pathways for sustainable hydrogen generation.

Hollow Mo-doped NiSx nanoarrays decorated with NiFe layered double-hydroxides for efficient and stable overall water splitting

“…[2][3][4] Compared with traditional hydrogen production methods, electrocatalytic water splitting has elicited research interest owing to its simple operation and environment-friendly products. 5,6 Water electrolysis comprises two half-reactions, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), 7,8 but the high potential and slow kinetics of the OER reduce the overall efficiency of water splitting, which encourages us to design more HER/OER catalysts with low overpotential. 9 Currently, noble metal Pt-based and RuO 2 /IrO 2 catalysts have been considered as the cutting-edge electrocatalysts for the HER and OER, respectively.…”

Repurposing metal containing wastes and mass-produced materials as electrocatalysts for water electrolysis

“…This is approximately the current density expected for a 10% efficient solar-to-fuels conversion device. 61 In more recent publications catalysts are being benchmarked at much higher current densities 62 of >500 mA cm −2 for periods of electrolysis of up to days 63 rather than hours to demonstrate commercial viability and these conditions should also be considered when reporting any new catalyst.…”

Selectively Growing a Highly Active Interface of Mixed Nb–Rh Oxide/2D Carbon for Electrocatalytic Hydrogen Production

“…Compared with traditional nanoparticles, mixed metal atom catalysts anchoring on supports with highly active interface have aroused considerable interests due to the unique characters such as the high atom utilization efficiency, large specific surface area, and extremely active and selective catalysis for various reactions. [ 11 , 12 , 13 ] Recently, many mixed metal atom catalysts have been reported and exhibited superior catalytic performance for HER. [ 11 , 12 , 13 , 14 ] For example, phosphate‐substituted β ‐NiMoO 4 exhibits the optimal hydrogen adsorption free energy and elevated HER activity due to the abundant active electronic states.…”

“…[ 11 , 12 , 13 ] Recently, many mixed metal atom catalysts have been reported and exhibited superior catalytic performance for HER. [ 11 , 12 , 13 , 14 ] For example, phosphate‐substituted β ‐NiMoO 4 exhibits the optimal hydrogen adsorption free energy and elevated HER activity due to the abundant active electronic states. [ 14 ] Ru‐Mo 2 C supported on carbon nanotube (Ru‐Mo 2 C@CNT) showed superior HER performance to commercial Pt/C in alkaline electrolyte.…”