P‑Block\nAluminum Single-Atom Catalyst for Electrocatalytic\nCO<sub>2</sub> Reduction with High Intrinsic Activity

Atomically dispersed transition metal\nsites on nitrogen-doped carbon\ncatalysts hold great potential for the electrochemical CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR) to CO due to their encouraging\nselectivity. However, their intrinsic activity is restricted by the\nhurdle of the high energy barrier of either *COOH formation or *CO\ndesorption due to the scaling relationship. Herein, we discover a\np-block aluminum single-atom catalyst (Al–NC) featuring an\nAl–N<sub>4</sub> site that enables disentangling this hurdle,\nwhich endows a moderate reaction kinetic barrier for *COOH formation\nand *CO desorption, as validated by in situ attenuated total reflection\ninfrared spectroscopy and theoretical simulations. As a result, the\ndeveloped Al–NC shows a CO Faradaic efficiency (FE<sub>CO</sub>) of up to 98.76% at −0.65 V vs RHE and an intrinsic catalytic\nturnover frequency of 3.60 s<sup>–1</sup> at −0.99 V\nvs RHE, exceeding those of the state-of-the-art Ni–NC and Fe–NC\ncounterparts. Moreover, it also delivers a partial CO current of 309\nmA·cm<sup>–2</sup> at 93.65% FE<sub>CO</sub> and 605 mA\nat >85% FE<sub>CO</sub> in a flow cell and membrane electrode assembly\n(MEA), respectively. Strikingly, when using low-concentration CO<sub>2</sub> (30%) as the feedstock, this catalyst can still deliver a\npartial CO current of 240 mA at >80% FE<sub>CO</sub> in the MEA.\nConsidering\nthe earth-abundant character of the Al element and the high intrinsic\nactivity of the Al–NC catalyst, it is a promising alternative\nto today’s transition metal-based single-atom catalysts.