Bimetallic Atom Dual-Doped MoS2-Based Heterostructures as a High-Efficiency Catalyst To Boost Solar-Assisted Alkaline Seawater Electrolysis

Abstract

For a large-scale production of green hydrogen via water splitting, seawater, because of its low-cost and abundant nature, is an attractive alternative to freshwater. An effective coordination purposely modulated electrocatalyst with high catalytic activity and selectivity is required to overcome the undesirable chlorine ion oxidation reaction that critically hampers electrolysis performance at the anode side. Herein, we reveal that dual-atomically dispersed palladium (Pd) and ruthenium (Ru) over two-dimensional MoS2 shelled CoNi alloy nanowires can obtain tailored properties to impressively improve hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities. The catalyst exhibits overpotentials for the HER and OER as low as 89 and 230 mV at 10 mA·cm–2 in alkaline freshwater, respectively, along with favorable stability. Theoretical studies indicate that dual-atomically dispersed Pd and Ru in MoS2 modifies S sites to be advantageous centers for optimum hydrogen adsorption, thus improving the catalytic activities. The electrolyzer of CoNi@MoS2–PdSARuSA(+,−) delivers a current response of 10 mA·cm–2 at small cell voltages of 1.45, 1.54, and 1.54 V along with high solar-to-hydrogen conversion efficiencies of 17.66, 17.71, and 18.14% in alkaline freshwater, simulated seawater, and natural seawater, respectively, beyond Pt/C(−)//RuO2(+) behaviors as well as previous reports.