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A graphitized hierarchical porous carbon material supported with a transition metal was prepared by a one-pot method, and it might show potential application in electrochemical conversion.

Local coordination environments of isolated metal atoms in single-atom catalysts (SACs) play decisive roles for their catalytic performance. By varying the morphology and P and N heteroatom doping of the CeO2 support, here we showed that the activity of Pt single atoms on spherical CeO2 is about 7 times higher than that on CeO2 nanorods in hydrogenation of phenylacetylene. Doping the spherical CeO2 support using N is more effective than using P, and could enhance the activity by another 3.3 times, which was 2.6-times even higher than that of spherical CeO2 supported Pt clusters. Diffuse reflectance infrared Fourier transform spectroscopy of chemisorbed CO and X-ray photoelectron spectroscopy showed that N doping induced an increase of the electron density of Pt single atoms, opposite to the effect of P doping. H–D exchange and temperature-programmed reduction of hydrogen revealed that a large enhancement of hydrogen dissociation activity and hydrogen spillover by N doping are both essential for promoting the activity for catalytic hydrogenation.

Lignin primarily composed of methoxylated phenylpropanoid subunits is an abundant biomass that can be used to produce aromatics. Herein, a series of non-precious bimetallic Ni–Fe/AC catalysts were prepared for efficiently depolymerizing lignin. When organosolv birch lignin was used to determine the efficiency of the catalysts in methanol solvent, the Ni1–Fe1/AC (the ratio of Ni and Fe was 1 : 1) achieved the highest total yield of monomers (23.2 wt%, mainly propylguaiacol and propylsyringol) at 225 °C under 2 MPa H2 for 6 h. From GPC analysis, it is also proved that lignin was efficiently depolymerized. The Ni–Fe alloy structure was formed according to XRD, HRTEM, H2-TPR and XPS characterization. Based on the model compounds’ tests, the Ni1–Fe1/AC catalyst showed high efficiency in ether bond cleavage without hydrogenation of aromatic rings which could be attributed to the synergistic effect of Ni and Fe on the alloy structure. The total yield of monomers by using the Ni1–Fe1/AC catalyst reached 39.5 wt% (88% selectivity to PG and PS) when birch wood sawdust was used as the substrate.