‘Hydrogen evolution’ may provide a sustainable energy supply

Researchers have discovered a metal-free catalyst, suitable for commercial application, which can play a part in splitting water to produce hydrogen electrochemically — via a process called the hydrogen evolution reaction (HER).

A study led by Shizhang Qiao of the University of Adelaide and including Yihan Zhu and Yu Han of KAUST, Thuwal, Saudi Arabia, tested a catalyst for HER consisting solely of carbon and nitrogen.

Hydrogen is potentially the planet’s most sustainable energy source. It has a higher energy density than other fuels, does not emit pollutants when burnt, and, as a component of water, is plentiful.

HER typically requires efficient catalysts and platinum has historically provided the best results, but is scarce and expensive. Other transition metals such as nickel or molybdenum are less efficient and susceptible to corrosion.

Hybrids of graphitic-carbon nitride and nitrogen-doped graphene catalysed HER as efficiently as most transition metal-based catalysts, without the susceptibility to corrosion. The catalytic properties of the hybrid material were a result of synergy between the two components. The carbon nitride provides sites for hydrogen adsorption whilst the N-graphene facilitates the transfer of electrons during the process of proton reduction.

“This study provides clear and solid evidence that, similar to precious metals, well-designed metal-free counterparts have great potential for highly efficient electrocatalytic HER, thus expanding the spectrum of catalysts for HER and other energy-related electrocatalytic reactions.” says Qiao.

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