Electronic and Structural Modification of Mn₃O₄ Nanosheets for Selective and Sustained Seawater Oxidation

Abstract

The accomplishment of seawater electrolysis to produce green hydrogen energy needs an efficient and durable electrocatalyst with high selectivity and corrosion resistance. Here we report a free-standing amorphous nanostructured oxygen evolution reaction (OER) electrocatalyst with microvoids developed by embedding Gd-doped Mn 3 O 4 nanosheets in a CuO-Cu(OH) 2 nanostructure array (Gd-Mn 3 O 4 @ CuO-Cu(OH) 2 . The surface oxygen vacancies modulated the electronic structure of the catalyst and offered active sites with optimal chemisorption energy to OER intermediates. The hierarchical surface structure provides a large specific surface area, high electrical conductivity, ionic mobility, intrinsic activity for each active site, and efficient charge transfer, leading to an outstanding catalytic performance. The enhanced structural, chemical, and corrosion resistance ensures effectiveness as an anode in direct seawater electrolysis. Specifically, it needs an input voltage of 1.63 V to deliver a current density of 500 mA cm −2 in alkaline seawater, with the stability of more than 75 h of continuous electrolysis without hypochlorite formation. The high Faradaic efficiency demonstrates its potential for hydrogen fuel production from seawater.

Selectivity of Oxygen Evolution Reaction on Carbon Cloth-Supported δ-MnO2 Nanosheets in Electrolysis of Real Seawater

“…It was reported that the relationship between Tafel slope, overpotential and current density can be expressed by the following equation: dlog (j)/d η = 2.303 RT/α nF, showing that Tafel slope is inversely proportional to charge transfer coefficient (α), namely the catalyst with high charge transfer ability has a small Tafel slope. Compared with 1M KOH electrolyte, the adsorption of pollutants, such as microorganisms, bacteria and small particles, in real seawater on the catalyst surface leads to degradation of catalytic performance and hinders the catalytic reaction, resulting in a larger Tafel slope [ 26 ].…”

Constructing a Highly Active Amorphous WO3/Crystalline CoP Interface for Enhanced Hydrogen Evolution at Different pH Values

“…The peaks at 533.24 and 531.8 eV are attributed to the O–H band and the metal-oxygen band, respectively. The asymmetric nature of the high-energy peak (corresponding to the hydroxyl species) is representative of surface oxygen vacancies . In addition, EPR tests of WO 3 /CoP (Figure S17) showed that the incorporation of W increases its oxygen vacancies, which is beneficial to improving the basic activity of the catalyst .…”

Roles of Metal Oxide Nanostructure-Based Substrates in Sustainable Electrochemical Water Splitting: Recent Development and Future Perspective

“…The nanostructured substrate has robust interface connections with the active sites. The growth and nucleation of nanostructures were controlled by the different parameters, e.g., applied potential and electrolyte concentrations . Wan et al also developed a Se-doped FeOOH electrocatalyst using a simple on-site electrochemical activation technique to attain a three-dimensional (3D) vertical Se-doped FeOOH nanosheet infrastructure on iron foam.…”