A water electrolysis system includes a water electrolytic stack, a water reservoir connected to the water electrolytic stack to supply water to the water electrolytic stack, a water circulation pump supplying the water in the water reservoir to the electrolytic stack; and a control unit configured to, during an operation stoppage of the electrolysis system, control the driving of the water circulation pump to convert the water in the electrolytic stack from an acidic condition to a neutral condition and to regulate a unit cell voltage of the electrolytic stack to a voltage such that an electrolysis reaction does not occur and a chemical state of an anode catalyst is stably maintained.

A water electrolysis system includes a water electrolytic stack, a water reservoir connected to the water electrolytic stack to supply water to the water electrolytic stack, a water circulation pump supplying the water in the water reservoir to the electrolytic stack; and a control unit configured to, during an operation stoppage of the electrolysis system, control the driving of the water circulation pump to convert the water in the electrolytic stack from an acidic condition to a neutral condition and to regulate a unit cell voltage of the electrolytic stack to a voltage such that an electrolysis reaction does not occur and a chemical state of an anode catalyst is stably maintained.

A method, a system, and an apparatus of certain embodiments are provided to recover water and carbon dioxide from combustion emissions. The recovery includes, among other things, electrolysis and carbon dioxide capture in a suitable solvent. The recovered water and carbon dioxide are subject to reaction, such as a catalytic methanation reaction, to generate at least methane.

A flow cell for reducing carbon dioxide may include a first chamber having a gold coated gas diffusion layer working electrode, a reference electrode, and a water-in-salt electrolyte comprising a super concentrated aqueous solution of lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI). A second chamber adjacent the first chamber has a gold coated gas diffusion layer counter electrode and the water-in-salt electrolyte. The second chamber being separated from the first chamber by a proton exchange membrane. A reservoir coupled to each of the first and the second chambers with a pump contains a volume of the water-in-salt electrolyte and a head space.

The present disclosure provides a hydrogen evolution electrode and a preparation method thereof. The preparation method includes the following steps: providing an electrolyte including Co(NO.sub.3).sub.2.Math.6H.sub.2O with a Co(NO.sub.3).sub.2 concentration of 0.005 mol L.sup.−1 to 0.015 mol L.sup.−1, MnCl.sub.2.Math.4H.sub.2O with a MnCl.sub.2 concentration of 0.005 mol L.sup.−1 to 0.01 mol L.sup.−1, KCl with a concentration of 0.003 mol L.sup.−1 to 0.008 mol L.sup.−1, and CH.sub.3CSNH.sub.2 with a concentration of 0.04 mol L.sup.−1 to 0.06 mol L.sup.−1; adjusting the electrolyte to a pH value of 6 to 7; providing a cathode in the form of a substrate; and conducting electrolysis in a cyclic voltammetry mode, thereby preparing the electrode for hydrogen production by water electrolysis through electrochemical deposition of a Co.sub.9-xMn.sub.xS.sub.8 nanosheet catalyst on the cathode substrate, where 1≤X≤7.

The present disclosure provides a hydrogen evolution electrode and a preparation method thereof. The preparation method includes the following steps: providing an electrolyte including Co(NO.sub.3).sub.2.Math.6H.sub.2O with a Co(NO.sub.3).sub.2 concentration of 0.005 mol L.sup.−1 to 0.015 mol L.sup.−1, MnCl.sub.2.Math.4H.sub.2O with a MnCl.sub.2 concentration of 0.005 mol L.sup.−1 to 0.01 mol L.sup.−1, KCl with a concentration of 0.003 mol L.sup.−1 to 0.008 mol L.sup.−1, and CH.sub.3CSNH.sub.2 with a concentration of 0.04 mol L.sup.−1 to 0.06 mol L.sup.−1; adjusting the electrolyte to a pH value of 6 to 7; providing a cathode in the form of a substrate; and conducting electrolysis in a cyclic voltammetry mode, thereby preparing the electrode for hydrogen production by water electrolysis through electrochemical deposition of a Co.sub.9-xMn.sub.xS.sub.8 nanosheet catalyst on the cathode substrate, where 1≤X≤7.

Processes for producing a metal superhydride include obtaining a metal or metal alloy electrode comprising one or more metal atoms, obtaining an electrolyte comprising hydrogen atoms, the electrolyte configured to kinetically suppress a hydrogen evolution reaction in the metal electrode, disposing the metal electrode in the electrolyte, applying pressure to the metal electrode and the electrolyte while the metal electrode is disposed in the electrolyte, and forming, based on applying the pressure, a metal superhydride comprising a plurality of hydrogen atoms of the electrolyte being bonded to each of the one or more metal atoms of the metal electrode. Generally, the metal superhydride is stable at a pressure less than 100 gigapascal (GPa).

Processes for producing a metal superhydride include obtaining a metal or metal alloy electrode comprising one or more metal atoms, obtaining an electrolyte comprising hydrogen atoms, the electrolyte configured to kinetically suppress a hydrogen evolution reaction in the metal electrode, disposing the metal electrode in the electrolyte, applying pressure to the metal electrode and the electrolyte while the metal electrode is disposed in the electrolyte, and forming, based on applying the pressure, a metal superhydride comprising a plurality of hydrogen atoms of the electrolyte being bonded to each of the one or more metal atoms of the metal electrode. Generally, the metal superhydride is stable at a pressure less than 100 gigapascal (GPa).

The invention relates to processes for the electrolysis of alkali chlorides by means of oxygen-depolarized electrodes, said processes having specific operating parameters for shut-down and restarting.

The invention relates to processes for the electrolysis of alkali chlorides by means of oxygen-depolarized electrodes, said processes having specific operating parameters for shut-down and restarting.