Hydrogen has been well recognized as a clean energy source. It is a promising sustainable alternative for relieving the severe energy crisis. Among all the hydrogen generation methods, water splitting is considered to be the most appropriate approach to achieve the clean H₂O-H₂-H₂O energy cycle. However, this technique is severely impeded by the lack of cost-effective, highly efficient, and durable catalysts required for the hydrogen evolution reaction (HER) and/or oxygen evolution reaction (OER). Hence, to develop catalysts with the above features is of great importance.

In this work, amorphous iron and cobalt based phosphate catalysts supported on the nickel foam were first developed using the colloidal chemical method targeting at the HER. The incorporation of Fe activates t...[ Read more ]

Hydrogen has been well recognized as a clean energy source. It is a promising sustainable alternative for relieving the severe energy crisis. Among all the hydrogen generation methods, water splitting is considered to be the most appropriate approach to achieve the clean H₂O-H₂-H₂O energy cycle. However, this technique is severely impeded by the lack of cost-effective, highly efficient, and durable catalysts required for the hydrogen evolution reaction (HER) and/or oxygen evolution reaction (OER). Hence, to develop catalysts with the above features is of great importance.

In this work, amorphous iron and cobalt based phosphate catalysts supported on the nickel foam were first developed using the colloidal chemical method targeting at the HER. The incorporation of Fe activates the catalytic ability of Co with higher charge transfer efficiency. Besides, the nanosheet morphology contributes a lot to the superior HER activity. Secondly, for the OER, the S-doped CoO_x nanorods synthesized on Ni foam via a template-assisted ion exchange method were developed. The sulfur incorporation, on the one hand, results in an apparent morphology evolution from nanorod to nanosheet, benefiting the OER performance with enlarged surface area. On the other hand, the electronic states modulation resulting from S doping plays a virtual role in OER activity promotion. For the goal of efficient overall water splitting, the optimum OER-active S-CoO_x-5h was integrated with NiCo-based phosphates as a bifunctional catalyst, which exhibits an outstanding activity, with only 1.61 V required at 10 mA/cm². Finally, a substrate strategy was applied by converting the original Ni foam to nickel phosphide (Ni-P). After loading with amorphous NiCoPi, a superior overall water electrolysis activity was obtained. And the Ni-P was verified to play an important role in enhanced activity by modulating the electronic state of NiCoPi and enlarging the active surface area. This work may lay a good foundation for developing catalytic systems towards large-scale industrial hydrogen production.