Dopamine-modified cobalt spinel nanoparticles as an active catalyst for the acidic oxygen evolution reaction.

The development of efficient non-noble metal electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions remains a critical challenge. Herein, we report a N-doped carbonaceous component-engineered Co3O4 (NCEC) catalyst synthesized via the sol-gel method. Dopamine hydrochloride (DA)-derived nitrogen-doped carbonaceous components were found to boost the OER performance of Co3O4. The optimized catalyst can reach an overpotential as low as 330 mV in 1 M H2SO4 at a current density of 10 mA cm-2 and maintains a good long-term stability of 60 hours. In particular, we found that the thermodynamic overpotential was inversely proportional to the content of oxidized N and pyridinic N, whereas it was directly proportional to the pyrrolic-N content. Our experiments and density functional theory (DFT) calculations confirm that the optimized catalyst exhibits enhanced charge transfer and the oxidized N species on Co3O4 is responsible for the high catalytic activity. Our study suggests that the performance of NCEC in acidic media can be further optimized by enhancing the content of oxidized N species.

Late Magmatic Activity in the Tarim Large Igneous Province: Evidence from the Puchang Granites.

The magmatic evolution sequence and tectonic activity background of the Permian Tarim large igneous province were discussed based on the research of petrogeochemistry, chronology, and zircon Lu-Hf isotope of two types of granite distributed in the Puchang V-Ti-magnetite deposit in the northwestern margin of Tarim. The results show that the two types are characterized by high silica, alkali, and potassium content. Both types of granites are enriched with light rare earth elements, including porphyritic granites with a negative anomaly of Eu and biotite monzogranites with a weak positive anomaly of Eu. The trace elements generally show that the large-ion lithophile elements are enriched relative to the high-field-strength elements, P and Ti are obviously depleted, and Rb, U, and K are relatively enriched. The zircon U-Pb age of porphyritic granites is 275.7 ± 1.0 Ma, the εHf(t) value ranges from -6.6 to -3.3, and the tDM2 ranges from 1469 to 1684 Ma. The zircon U-Pb age of biotite monzogranites is 268.9 ± 1.4 Ma. The εHf(t) value ranges from -1.2 to 0.5, and the tDM2 ranges from 1232 to 1340 Ma. The two types of granite were formed in a postcollisional extensional environment at the end of the early Permian, which is related to the Permian Tarim mantle activity and asthenosphere upwelling. The porphyritic granite was derived from an enriched lithospheric mantle; the biotite monzogranite was formed by the melting of mantle with crust contamination; and basalt and intrusive complexes in the research area were formed in an extensional intraplate rift environment.