The utilization of hydrogen energy is an important way to low carbon economy, and the development of active electrodes is the most critical step for efficient hydrogen evolution reaction. With the addition of KNO 3 as a capping agent, the exposed crystal facet of CuFe 2 O 4 is regulated, and the crystal facet (111) becomes dominant. Compared to CuFe 2 O 4 (3 1 1), CuFe 2 O 4 (111) exhibits low barrier of water dissociation and suitable *H binding strength, resulting in high intrinsic activity. Furthermore, the 3D printed electrodes show more excellent performance. At 3D printed CuFe 2 O 4 (111) electrode, the overpotential is only 152 mV (vs. reversible hydrogen electrode) at 100 mA cm −2 , and Tafel slope is as low as 33 mV dec -1 . In addition, 3D printed CuFe 2 O 4 (111) electrodes shows high stability. The superior performance of 3D printed CuFe 2 O 4 (111) electrodes originates from high intrinsic activity and more exposed active sites. This study provides a new path for the development of efficient, stable and inexpensive monolithic catalyst electrodes for alkaline hydrogen evolution.
The conversion of cellulose to platform chemicals has attracted much attention because of its renewability. This work proposed an earth-abundant cobalt disulfide as a heterogeneous catalyst for methyl levulinate production from cellulose. The highest yield of methyl levulinate reached 61 mol% under the tested conditions of 200 °C, 2 MPa initial pressure, 0.45 catalyst/cellulose mass ratio, and 3 h reaction time. The XRD and TEM analyses demonstrated the crystal facet (111) of cobalt disulfide as a robust active site, which was in good agreement with the highest acidity of the crystal facet (111) calculated by the work functions. The XPS characterization showed that the main chemical valence of cobalt disulfide responsible for the methyl levulinate production was the surface Co 2+ species. This study is valuable for the development of a recoverable catalyst for the cellulose to methyl levulinate process.
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