Using clean electricity to reduce CO2 to chemicals or fuels is becoming increasingly important to renewable energy applications and environmental protection. The challenge comes from the strong competition with the hydrogen evolution reaction in aqueous solutions, especially for those earth-abundant transition metals such as Ni, which dramatically lowers the CO2 reduction selectivity. Isolating the transition-metal single atoms into a graphene matrices can significantly tune their catalytic behaviors to favor the CO2-to-CO reduction pathway, reaching a high CO selectivity of more than 90%, and delivering a turnover frequency above 2.1 x 105 h-1 by employing an anion exchange membrane assembly and at a cell voltage of 2.78 V. Coupled with Li+-tuned Co3O4 oxygen evolution catalyst and powered by a commercial triple-junction solar cell, our artificial photosynthesis system achieves a peak solar-to-CO efficiency of 12.7% by using earth-abundant transition-metal electrocatalysts in a pH-equal system.

Isolated Ni single atoms in graphene matrices for high-performance CO2 reduction

256th National Meeting (2018)

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