Strong‐Proton‐Adsorption Co‐Based Electrocatalysts Achieve Active and Stable Neutral Seawater Splitting

Abstract

Direct electrolysis of pH‐neutral seawater to generate hydrogen is an attractive approach for storing renewable energy. However, due to the anodic competition between the chlorine evolution and the oxygen evolution reaction (OER), direct seawater splitting suffers from a low current density and limited operating stability. Exploration of catalysts enabling an OER overpotential below the hypochlorite formation overpotential (≈490 mV) is critical to suppress the chloride evolution and facilitate seawater splitting. Here, a proton‐adsorption‐promoting strategy to increase the OER rate is reported, resulting in a promoted and more stable neutral seawater splitting. The best catalysts herein are strong‐proton‐adsorption (SPA) materials such as palladium‐doped cobalt oxide (Co3–xPdxO4) catalysts. These achieve an OER overpotential of 370 mV at 10 mA cm−2 in pH‐neutral simulated seawater, outperforming Co3O4 by a margin of 70 mV. Co3–xPdxO4 catalysts provide stable catalytic performance for 450 h at 200 mA cm−2 and 20 h at 1 A cm−2 in neutral seawater. Experimental studies and theoretical calculations suggest that the incorporation of SPA cations accelerates the rate‐determining water dissociation step in neutral OER pathway, and control studies rule out the provision of additional OER sites as a main factor herein.

Coordination Tuning of Metal Porphyrins for Improved Oxygen Evolution Reaction

“…The oxygen evolution reaction (OER) is a fundamental process in natural and artificial energy conversion schemes [1–5] . Due to the slow kinetics of OER, efficient catalysts are required [6–17] . Terminal metal‐oxo species are generally considered as intermediates in OER [18–20] .…”

“…[1][2][3][4][5] Due to the slow kinetics of OER, efficient catalysts are required. [6][7][8][9][10][11][12][13][14][15][16][17] Terminal metal-oxo species are generally considered as intermediates in OER. [18][19][20] The nucleophilic attack of water or hydroxide on metal-oxo is a possible OÀ O bond formation process (Figure 1a).…”

Highly Durable and Efficient Seawater Electrolysis Enabled by Defective Graphene-Confined Nanoreactor

“…Green hydrogen production from water electrolysis combined with renewable energy sources like solar, wind, and marine power is regarded as a promising pathway for sustainable energy conversion. − Tremendous efforts have been attempted in using freshwater as the electrolyte feedstock, but its high cost and scarcity limit the development of large-scale water electrolysis. − To this end, seawater, as the most abundant feedstock (∼96.5% of the world’s water resource), has drawn increasing attention for solving the issues associated with freshwater. − However, the implementation of direct seawater electrolysis without external desalination and purification is fundamentally and technologically challenging due to the complicated composition of seawater, which is especially problematic for the anodic oxygen evolution reaction (OER) . The greatest challenge originates from the concentrated chloride ions (Cl – ) in seawater.…”

Cu2S Nanorods Decorated with NiFe-Layered Double Hydroxide Nanosheets as Bifunctional Electrocatalysts for Hydrogen Evolution in Alkaline Saline Water/Seawater

“…Electrocatalytic water splitting is considered to be one of the most promising strategies for obtaining carbon-free and renewable hydrogen energy. − Due to the high price and lack of resources, the large application of commercial precious metal-based electrocatalysts is limited. − Therefore, it is very promising for us to develop low-price and high-efficiency nonprecious metal-based electrocatalysts. However, large-scale electrolysis brings great pressure on water resources due to the shortage of freshwater resources in the world.…”