Biochar-supported Cu₂O nanocrystallites as a platinum-free electrocatalyst for hydrogen evolution

Hydrogen technology is significantly influencing the transformation of the energy sector, supported by recent advancements in global infrastructure. The production of sustainable hydrogen is contingent upon the development of cost-effective electrode materials that can replace platinum. This study assesses the potential of Cu2O nanocrystallite catalysts as an economical, non-platinum alternative for hydrogen generation through the water-splitting process. The characterization of the materials was conducted using a combination of spectroscopic, microscopic, and electrochemical techniques. Biochar was employed as a supporting carbon to serve as the gas diffusion layer, while sulfonated polyether ether ketone (SPEEK) was utilized as the binder on the catalytic interface. The introduction of Cu2O led to a significant reduction in the overpotential for hydrogen generation, decreasing it from −0.60 V to −0.40 V (versus RHE), which corresponds to a 33.33% improvement. Furthermore, the addition of Pd black led to a further reduction of the onset potential to −0.1 V vs RHE, about 75% decrease. Post-reaction analysis indicated a dramatic decrease in the onset potential from −0.40 V to −0.073 V (versus RHE) in the absence of the Pd catalyst. This final value was observed as highly competitive against those of some of the previously explored catalytic materials in the field. Furthermore, post-reaction after exposure to air during storage lowers the current density by 26.09% (relating to a change from 6.40 to 22.3 kΩ). Thus, it is recommended that the catalyts should be stored in an air-tight environment to avoid loss of activity after use.