近日，美国纽约州立大学周光文团队研究了依赖气体的氧化物还原性的原子动力学。该项研究成果发表在2025年8月20日出版的《自然》杂志上。

了解氧化物还原对推进金属生产、催化和能源技术至关重要。虽然一氧化碳（CO）和氢（H₂）是广泛使用的还原剂，但它们的工作机制通常被认为是相似的，都涉及晶格氧去除。然而，由于人们对用氢气替代CO以降低二氧化碳排放的兴趣日益浓厚，区分特定气体的减排途径至关重要。然而，在反应气体和高温条件下捕捉这些原子尺度的过程仍颇具挑战性。

研究组开发了环境透射电子显微镜，它能够实时、原子分辨率成像气固氧化还原反应，直接可视化NiO中依赖气体的氧化物还原动力学。他们发现CO驱动表面成核和金属Ni岛的生长，导致自限制的表面金属化。相反，H₂激活了一个耦合的表面到体转化，其中来自解离H₂的质子渗透到氧化物晶格中，促进表面生成的氧空位向内迁移，从而实现体金属化。相比之下，CO形成的氧空位仍然被限制在表面附近，其迅速形成金属镍层，阻止进一步还原。这些结果揭示了CO和H₂的不同原子路径，并提供了可能指导冶金工艺和催化剂设计的见解。

附：英文原文

Title: Atomic dynamics of gas-dependent oxide reducibility

Author: Chen, Xiaobo, Wang, Jianyu, Patel, Shyam Bharatkumar, Ye, Shuonan, Wu, Yupeng, Zhou, Zhikang, Qiao, Linna, Wang, Yuxi, Marinkovic, Nebojsa, Li, Meng, Hwang, Sooyeon, Zakharov, Dmitri N., Ma, Lu, Wu, Qin, Boscoboinik, Jorge Anibal, Yang, Judith C., Zhou, Guangwen

Issue&Volume: 2025-08-20

Abstract: Understanding oxide reduction is critical for advancing metal production1,2, catalysis3,4 and energy technologies5. Although carbon monoxide (CO) and hydrogen (H2) are widely used reductants, the mechanisms by which they work are often presumed to be similar, both involving lattice oxygen removal6,7,8,9. However, because of growing interest in replacing CO with H2 to lower CO2 emissions, distinguishing gas-specific reduction pathways is critical. Yet, capturing these atomic-scale processes under reactive gas and high-temperature conditions remains challenging. Here we use environmental transmission electron microscopy, which is capable of real-time, atomic-resolution imaging of gas–solid redox reactions10,11,12,13,14,15,16, to directly visualize the gas-dependent oxide reduction dynamics in NiO. We show that CO drives surface nucleation and the growth of metallic Ni islands, leading to self-limiting surface metallization. Conversely, H2 activates a coupled surface-to-bulk transformation, where protons from dissociated H2 infiltrate the oxide lattice to promote the inward migration of surface-generated oxygen vacancies and enabling bulk metallization. By contrast, oxygen vacancies formed by CO remain confined near the surface, where they rapidly form a metallic Ni layer that inhibits further reduction. These results reveal distinct atomistic pathways for CO and H2 and provide insights that may guide metallurgical processes and catalyst design.

DOI: 10.1038/s41586-025-09394-0

Source: https://www.nature.com/articles/s41586-025-09394-0