Schottky junction catalyst promotes hydrogen production by non-precious metals in water electrolysis

Electrically driven water electrolysis has attracted attention as an environmentally friendly method for hydrogen production, as high-purity hydrogen is essential to resolving the energy crisis. However, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water electrolysis typically require precious metals as electrocatalysts. This limitation has led researchers to focus on developing effective non-precious metal catalysts to increase both the efficiency and cost-effectiveness of water electrolysis.

Carbon nitride (g-C3N4) has been widely studied for its tunable semiconducting properties, but its catalytic activity for HER and OER is low due to its limited charge mobility and low specific surface area. In a study published in the journal Advanced Powder Materials, a team of researchers from Xi’an University of Architecture and Technology in China used targeted doping and interfacial coupling strategies to develop two active Schottky junction electrocatalysts (B–C3N4@Fe3C and S–C3N4@Fe3C).

“For the first time, a strategy is proposed to rationally construct the built-in electric field and space charge region to enhance the redox reaction rate on g-C3N4 hollow nanotubes,” said Xinning Yun, the study’s lead author.

The team’s efforts confirmed that the internally supported g-C3N4 hollow nanotubes have abundant active regions that facilitate rapid proton and mass transfer.

“Through direct doping with B and S, we precisely tuned the semiconducting properties of g-C3N4 and formed typical n-type and p-type band structures,” Yun continues. “This tuning provided an excellent platform for constructing surface-functionalized B-C3N4@Fe3C and S-C3N4@Fe3C Schottky junction catalysts.”

The results revealed that the coupling of Fe3C and g-C3N4 optimized the energy level of g-C3N4, changed the interfacial charge distribution of g-C3N4@Fe3C, and enriched OH- and H+ at the solid-liquid reaction interface.In particular, the B-C3N4@Fe3C and S-C3N4@Fe3C catalysts exhibited stable HER activity and high selectivity for OER under alkaline medium.

“The B-C3N4@Fe3C||S-C3N4@Fe3C pair only requires a low voltage of 1.52 V to achieve efficient water electrolysis at 10 mA cm-2, highlighting its excellent electrocatalytic activity and promising stability under long-term alkaline water splitting conditions,” said Guangping Yang, first author of the study.