Tailoring the D-Band Center of Sol-Gel-Derived Nd-Doped NiO for Ultra-Low-Temperature N2O Decomposition with Improved Impurity Resistance

Abstract Mitigating the profound environmental impact of greenhouse gas nitrous oxide (N2O) emissions necessitates the design of highly active, low-temperature, and impurity-tolerant decomposition catalysts. In this work, sol-gel-derived neodymium-incorporated nickel oxide (NdxNi) catalysts were systematically developed for direct N2O decomposition. The optimal Nd0.06Ni achieves 90% N2O conversion (T90) at a remarkably low temperature of 275 °C. Compared to bare NiO, it exhibits a drastically suppressed apparent activation energy (Ea) declining from 97.15 to 61.31 kJ/mol, and a 1.5-fold increase in turnover frequency (TOF). In the individual presence of NO, O2, or H2O, Nd0.06Ni exhibited improved impurity resistance relative to pristine NiO, maintaining T90 values within 315–360 °C. However, simultaneous exposure to the three impurities substantially suppressed the N2O conversion, whereas the activity largely recovered after the impurities were removed, indicating reversible inhibition under the present conditions. Crucially, density functional theory (DFT) calculations, underpinned by d-band center analysis, reveal the intrinsic catalytic mechanism: Nd incorporation shifts the d-band center of surface Ni sites downward from −2.41 eV to −2.56 eV. This moderate electronic modulation optimally weakens the over-strong Ni–O bond, substantially reducing the energy required for O2 desorption (from 5.19 to 4.58 eV) and thus accelerating the Ni2+/Ni3+ redox cycle. This work provides fundamental insights and a viable strategy for designing ultra-low-temperature catalysts with improved impurity resistance for practical N2O abatement.