Highly Active Pt‐Fe Catalysts Towards CO Preferential Oxidation with an Ultra‐Wide Temperature Window

Abstract

Abstract Preferential oxidation of CO in H 2 (CO‐PROX) is a promising solution to remove the residual CO in the feed stream to avoid Pt poisoning in proton‐exchange‐membrane fuel cells (PEMFCs), in which the development of high‐efficiency catalysts with a wide temperature window remains a great challenge. Herein, we report a Fe(OH) x modified Pt clusters (∼1.6 nm) catalyst supported on MgAlO x (denoted as MA) derived from PtFeMgAl‐layered double hydroxides (PtFeMgAl‐LDHs) precursor, which is featured with abundant Pt δ + –(OH) x –Fe 3+ interfacial sites. Impressively, the optimal catalyst Pt‐Fe(OH) x /MA exhibits exceptional catalytic performance towards CO‐PROX, which can completely remove CO in a H 2 ‐rich stream with an ultra‐wide full CO conversion window (25°C−225 °C) at a rather high space velocity (130 000 mL g cat −1 h −1 ). The mass‐specific activity reaches to 9.09 mol CO g Pt −1 h −1 at 25 °C, which is preponderant to the state‐of‐the‐art catalysts. In addition, a 240 h stream‐on‐line test over Pt‐Fe(OH) x /MA shows a satisfactory stability. A comprehensive investigation based on in situ experimental studies and theoretical calculations reveals that the –OH group at the Pt δ + –(OH) x –Fe 3+ interfacial site is easily bound to the linearly‐adsorbed CO at the adjacent Pt δ + site to form carboxylate intermediate, followed by its decomposition to CO 2 . Meanwhile, the generated coordination unsaturated Fe 2+ site facilitates the activation cracking of O 2 molecule without energy barrier. A structure design strategy of interfacial synergistic catalysis towards CO‐PROX is proposed in this work, which shows fundamental significance and application prospects in hydrogen purification.