Nickel Catalysts at the Crossroads: Sabatier Methanation, Carbide Phases, and Prospects for Methanol Synthesis

Abstract

Nickel is a cornerstone of heterogeneous catalysis and remains one of the most practical metals for hydrogenation chemistry. In CO₂ hydrogenation, however, Ni has long been associated with the Sabatier reaction, favoring the formation of CH₄. While methane is relevant for energy storage and compatible with existent infrastructure, it is often less desirable than CO or oxygenates as chemical feedstocks. As the field of CO₂ utilization evolves toward a circular carbon economy, this raises a critical question: can nickel catalysts be reengineered to move beyond methanation and enable access to more valuable products? This Account addresses that question by revisiting Ni catalysis from a broader and more forward-looking perspective. Although methanation remains the most studied reaction with Ni, the continued focus on CH₄ as the primary product no longer reflects the full potential of this metal. Instead, selective formation of CO and methanol offers more versatile pathways for downstream chemical synthesis and fuel production. Achieving such selectivity requires overcoming the intrinsic tendency of Ni to strongly bind and hydrogenate CO intermediates, leading preferentially to methane. We examine how Ni can be repurposed for alternative CO₂ valorization pathways by controlling the features that most strongly determine selectivity: (i) particle size and surface-site distributions, which regulate the extent of deep hydrogenation, (ii) carbon incorporation in and on Ni, ranging from surface-carburized states to carbide-like motifs that weakens CO adsorption and shifts selectivity toward CO, (iii) carbon/metal interfaces, such as N-doped carbon coatings, which modify adsorption properties and interfacial reaction environments, and (iv) alloy and intermetallic chemistry, particularly Zn- and Ga-containing phases, which impose new adsorption energetics and can enable methanol synthesis under appropriate conditions. Beyond these established strategies, emerging insights into nickel carbide phases introduce an underexplored dimension in catalyst design. Their distinct electronic and structural properties provide opportunities to tune selectivity in ways not accessible with metallic Ni alone. At the same time, advances in operando characterization and computational modeling are beginning to reveal the dynamic nature of Ni surfaces under reaction conditions, offering new pathways for rational catalyst design. Throughout this Account, we highlight lessons from our laboratory alongside complementary advances in the field, emphasizing unifying design principles that can guide the identification of the targeted active state for CO₂ hydrogenation. By integrating these perspectives, we propose that nickel should not be viewed solely as a methanation catalyst, but as a versatile and tunable platform for CO₂ conversion. This Account summarizes previously published results from our group and others; no new experimental data are presented herein.