Water electrolysis remains a key component in the societal transition to green energy. Membrane electrolyzers are the state‐of‐the‐art technology for water electrolysis, relying on 80 °C operation in highly alkaline electrolytes, which is undesirable for many of the myriad end‐use cases for electrolytic water splitting. Herein, an alternative water electrolysis process, decoupled electrolysis, is described which performed in mild acidic conditions with excellent efficiencies. Decoupled electrolysis sequentially performs the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), at the same catalyst. Here, H⁺ ions generated from the OER are stored through pseudocapacitive (redox) charge storage, and released to drive the HER. Here, decoupled electrolysis is demonstrated using cheap, abundant, TiO₂ for the first time. To achieve decoupled acid electrolysis, ultra‐small anatase TiO₂ particles (4.5 nm diameter) are prepared. These ultra‐small TiO₂ particles supported on a carbon felt electrode show a highly electrochemical surface area with a capacitance of 375 F g⁻¹. When these electrodes are tested for decoupled water splitting an overall energy efficiency of 52.4% is observed, with excellent stability over 3000 cycles of testing. This technology can provide a viable alternative to membrane electrolyzers—eliminating the need for highly alkaline electrolytes and elevated temperatures.

For transport needs the hydrogen is mostly stored in a compressed (at 350-700 bars) form, while methods for its storage at lower pressures are rapidly developing. In particular, nanoporous oxides and zeolites, which do not normally absorb notable amount of hydrogen, with a small Pd additive or ion exchange demonstrate enhanced hydrogen adsorption properties. An original thermogravimetric method has been developed to study the hydrogen adsorption in zeolite, consisting of its heating in the inert gas (argon, nitrogen) flow and cooling in the hydrogen atmosphere. It is found that natural zeolite (clinoptilolite) with Mg-ion exchange possesses a high adsorption capacity for hydrogen - up to 6.2 wt%, which is explained by its encapsulation in zeolite pores. The FTIR spectra of the hydrogen-treated samples have shown new absorption bands at 2340 and 2360 cm^-1.