Hydrogen is produced by electrolysis and photolysis water splitting techniques with advantages for controlling energy resources, high energy density, ease of storage and transportation, and low pollution. The electrochemical process separates water into hydrogen and oxygen gases to store and transport to a fuel cell or combustion chamber; the by-products are mostly water.

The hydrogen technology requires highly active and stable catalysts for hydrogen evolution reaction (HER) in water-splitting devices made of Platinum (Pt), a rare element that makes the technology expensive. For efficient hydrogen technology, a cheap and environmentally friendly (HER) catalyst is one of the solutions. Current catalyst production involves toxic chemicals impacting the ecosystem.

In a study published in Opto-Electronic Advances, a research group led by Prof. LI Wei from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) proposed a laser-induced periodic surface structured electrodes with 45 % energy saving in electrochemical fuel generation through field localization.

Researchers fabricated laser induced periodic surface structures (LIPSSs) on Ni-foam (NF) and controlled geometric parameters with localized electric field-induced modulation in the reagent concentration (LEFIRC) on electrode. The hierarchical structured LIPSSs electrodes with periodic ridges and grooves of 100-300 nm widths are covered with spherical nanoparticles (NPs) sized 3-94 nm diameters. The LEFIRC effect enhances the performance of electrochemical fuel generation of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).

The optimized LIPSS patterned electrode achieves a hydrogen generation rate of 3×1016 molecules cm-2s-1 (at current density: 10 mA/cm2). LEFIRC effect reinforce LIPSS patterned electrodes as a substrate to support and boost the performance of the electrocatalyst. The HER model electrocatalyst on the LIPSS patterned NF substrate demonstrated 130 mV (40 %) of lower 10 overpotentials in the HER and high stability. And OER model electrocatalyst on the LIPSS patterned NF substrate required 100 mV (25 %) more melancholy 10 overpotentials in the OER with better stability.

Importantly, when two LIPSS patterned electrodes were assembled simultaneously as anode and cathode in a cell, it requires a low electric potential of 330 mV over a similar cell made of cpristine NF electrodes to drive 10 mA/cm2 in the overall water splitting figure.

The patterned LIPSS electrocatalysts operate at significantly lower electrical potential, proving the femtosecond laser patterning approach has a high possibility of green catalyst generation.