Unified Perspectives on Spin Polarization in Heterogeneous Photo/Electrocatalysis

Abstract Spin polarization offers a revolutionary pathway for enhancing photocatalytic and electrocatalytic performance through spin‐selective control of charge dynamics and reaction kinetics. Despite rapid advances, a unified mechanistic framework connecting spin effects across these domains remains underdeveloped. This review outlines recent breakthroughs in spin‐regulated mechanisms for energy and environmental catalysis. First, in photocatalysis, spin‐polarized charge carriers are primarily generated within the bulk phase upon photoexcitation, facilitated by its intrinsic spin‐dependent band structure. Subsequently, the efficiency of catalytic process is collectively governed by spin‐dependent charge separation and surface reactions adhering to spin conservation rules. Conversely, in electrocatalysis, spin‐polarized current is externally injected from a magnetic electrode. Here, spin filtering at the interface significantly influences, and can even dictate, reaction pathways selection—the spin state of active sites directly determines the spin‐selective adsorption configuration and strength of reactant molecules, as well as the stability of key reaction intermediates (*O, *OH) and their subsequent bond breaking/forming energy barriers. The core divergence lies in the spin carrier origin, and quantum‐level selectivity control offers complementary strategies for breaking scaling relations in energy catalysis. Finally, a cross‐disciplinary framework bridging spin‐photo/electrocatalysis is established, highlighting three strategic directions: dynamic spin‐state modulation, field‐coupling mechanisms, and scalable design of spin‐polarized systems for sustainable applications.