Repurposing e-waste cathodes as catalysts for CO2 reduction via the reverse water-gas shift reaction†
Abstract
The reverse water–gas shift (RWGS) reaction offers a promising pathway for utilising green H2 to reduce CO2 into CO, a valuable precursor for e-fuel production. Conventional catalyst synthesis methods, however, often rely on costly and complex procedures using fine chemical precursors. In this study, we repurpose retired ternary lithium-ion battery cathodes (rTLIBCs), prevalent e-waste from the electric vehicle industry, as catalysts for the RWGS reaction. Using a straightforward method of mixing the rTLIBC material with Al2O3 powder, we successfully synthesise xNCM/Al2O3 catalysts with high CO2 conversion and CO selectivity. Notably, the 10NCM/Al2O3 catalyst demonstrates the highest CO space-time yield at 450–600 °C, with stable performance across long-term tests, maintaining CO2 conversion, CO selectivity, and CO space-time yield. The performance of our prepared catalyst is comparable to that of the best catalysts synthesised using fine chemicals. The high catalytic performance is attributed to the synergistic effect of a Ni–Co bimetallic alloy formed during pretreatment, strong metal–support interaction, and alkali metal Li. Ni–Co alloy formation optimises the catalytic activity and selectivity, the metal–support interaction enhances CO2 activation, and Li boosts basicity and fine-tunes the reaction pathway. This study validates that rTLIBCs are a viable raw material for practical RWGS catalyst synthesis, providing a sustainable alternative for e-waste utilisation.