Efficient and Stable Water Oxidation on Nd-O-Fe via 4f-2p-3d Gradient Orbital Coupling Mediated Lattice Oxygen Mechanism

This work regulates electronic structure and oxygen vacancies of Fe 2 O 3 via Nd-O-Fe 4f-2p-3d orbital coupling, promoting OER mechanism from AEM to LOM and clarifying the intrinsic catalytic origin. • The as-prepared Nd-Fe 2 O 3 @C shows low overpotential and favorable OER activity, with stable operation over 300 h at 10 mA cm -2 , presenting remarkably improved stability. • In-situ IR, in-situ Raman combined with DFT calculations demonstrate that Nd doping upshifts the Fe d-band center and reduces the Fe spin state, significantly lowing the adsorption energy of Fe 2 O 3 toward *OH and *O species. The development of highly active and stable non-precious metal-based catalysts for the oxygen evolution reaction (OER) is crucial for achieving efficient and low-cost hydrogen production through electrolysis. Herein, the temperature-programmed calcination approach is employed to synthesize the target catalyst of Nd-doped Fe 2 O 3 on graphitic carbon (Nd-Fe 2 O 3 @C). This Nd-Fe 2 O 3 @C presents excellent OER performance with a low overpotential of 359 mV at 10 mA cm −2 , a small Tafel slope of 70.31 mV/dec, and long-term stability (over 300 h). Tetramethylammonium hydroxide (TMAOH) measurements coupled with in-situ characterizations capture the dynamic evolution of key oxygen intermediates, verifying that Nd doping creates oxygen vacancies and thereby triggers the lattice oxygen oxidation mechanism (LOM). Density functional theory (DFT) calculations revealed that Nd doping increases antibonding orbital occupancy, which leading to weaker adsorption of oxygen intermediates and facilitate *OH and *O desorption during the OER. This work establishes oxygen vacancy engineering as effective strategy for robust water oxidation through LOM pathway. The Nd-Fe 2 O 3 @C with 4f–2p–3d gradient orbital coupling catalyst exhibits a low overpotential (η 10  = 359 mV), a small Tafel slope (70.31 mV dec -1 ) and outstanding long-term catalytic stability (300 h). DFT calculations demonstrate that Nd doping upshifts the Fe d-band center and reduces the Fe spin state, significantly lowing the adsorption energy of Fe 2 O 3 toward *OH and *O species. Download: Download high-res image (293KB) Download: Download full-size image