Strategically Constructing Alkali-Metal Interfacial Bridges to Boost Photocatalytic CO2 Methanation on Supported Ni─Ru Bimetallic Catalysts.

Abstract

Efficient photocatalytic conversion of CO₂ into CH₄ is crucial yet challenging due to the complex multi-electron transfer processes and sluggish intermediate transformation. Herein, an innovative strategy is introduced to dramatically enhance photocatalytic CO₂ methanation by constructing interfacial alkali-metal bridges (Na_inter) between Ni and Ru nanoparticles over ZrO₂ surface. By selectively introducing and subsequently removing excessive surface Na species, stable interfacial Na species are retained, forming a distinctive Ni⁰─Ni^δ+─Na_inter─O─Ru electronic bridge. Comprehensive structural and electronic characterizations (XRD, TEM, XAFS, XPS, DRIFTS) demonstrate that the interfacial Na bridge significantly improves electronic communication between Ni and Ru, enhances charge separation efficiency, optimizes CO₂ adsorption, and lowers activation barriers for key intermediates. As a result, the optimized catalyst (0.2Na─Ni─Ru/ZrO₂) achieves an exceptionally high CH₄ production rate of 1882.7 µmol·g^-1·h^-1, ≈15-fold that of the Na-free catalyst, with excellent stability and durability. DFT calculations reveal that the Na_inter site effectively stabilizes reactive intermediates, greatly accelerating formate to CO conversion and reshaping the reaction pathway. This work highlights alkali-metal-mediated interfacial engineering as a versatile approach to enhance the synergy in multi-component catalysts, opening a new avenue for advanced photocatalytic CO₂ reduction.