Improved Alkaline Seawater Splitting of NiS Nanosheets by Iron Doping

Abstract

Seawater electrolysis driven by renewable electricity is deemed a promising and sustainable strategy for green hydrogen production, but it is still formidably challenging. Here, we report an iron-doped NiS nanosheet array on Ni foam (Fe–NiS/NF) as a high-performance and stable seawater splitting electrocatalyst. Such Fe–NiS/NF catalyst needs overpotentials of only 420 and 270 mV at 1000 mA cm–2 for the oxygen evolution reaction and hydrogen evolution reaction in alkaline seawater, respectively. Furthermore, its two-electrode electrolyzer needs a cell voltage of 1.88 V for 1000 mA cm–2 with 50 h of long-term electrochemical durability in alkaline seawater. Additionally, in situ electrochemical Raman and infrared spectroscopy were employed to detect the reconstitution process of NiOOH and the generation of oxygen intermediates under reaction conditions.

Recent advances of bifunctional electrocatalysts and electrolyzers for overall seawater splitting

“…Thus, NiFeS/NF can drive the industrially demanded current density of 500 mA cm −2 at overpotentials of 300 and 347 mV cm −2 for HER and OER in alkaline seawater. Additionally, our group reported a bifunctional catalyst Fe–NiS/NF, 78 which could attain a current density of 1000 mA cm −2 at 1.88 V during the overall seawater splitting.…”

Fe1–xNix(PO3)2/Ni2P Heterostructure for Boosting Alkaline Oxygen Evolution Reaction in Fresh Water and Real Seawater at High Current Density

“…The HRTEM image of Fe 1−x Ni x (PO 3 ) 2 /Ni 2 P/NF after 3000 OER CV cycles (Figure S14) demonstrates that there exists amorphous phases, which may be NiOOH and FeOOH generated during the OER process, and NiOOH and FeOOH can be the active sites for OER. 3 In Figure S14b, it can be observed that the lattice spacings of 0.218 and 0.248 nm correspond to the (0 0 4) and (1 3 1) crystal planes of Fe(PO 3 ) 2 , while the lattice spacing of 0.192 nm corresponds to the (2 1 0) crystal plane of Ni 2 P. In addition, as shown in Figure S15, the content of element P in Fe 1−x Ni x (PO 3 ) 2 /Ni 2 P/ NF after 3000 OER CV cycles is significantly reduced due to the leaching of metaphosphate during the OER process. 43,44 The contents of each element in Fe 1−x Ni x (PO 3 ) 2 /Ni 2 P/NF after 3000 OER CV cycles were Ni 18.55, Fe 20.65, O 60.55, and P 0.24% (Figure S16).…”

“…The combustion of fossil energy such as coal and petroleum has brought a series of environmental problems and energy crises; thus, there is an urgent need to find efficient clean energy. , Hydrogen is a renewable and clean energy source with high energy density. At present, water electrolysis is an effective hydrogen production technology. − Seawater, as a very rich reserve, accounts for 97% of global water resources, which is a potential resource for water electrolysis . Electrolysis of water contains two separate half-reactions, which are the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode.…”

Branched Porous Ni3N as a Catalytic Electrode for Selective Semidehydrogenation of Tetrahydroisoquinoline

“…Water splitting driven by electric energy, especially the electric energy generated from the intermittent but sustainable energy sources such as wind and solar energy, has got much attention since it can greenly produce hydrogen that is an environmentally friendly energy carrier. − However, for water splitting, the anode end with an oxygen evolution reaction (OER) needs a high overpotential, which greatly limits the total energy efficiency for hydrogen production on the other end. − In addition, the oxygen produced at the anode end is relatively low-valuable. Thus, integrating a useful anodic reaction with low overpotential will not only improve water-splitting efficiency inducing the generation of hydrogen, but will also provide value-added products. − …”