The effect of organic additives on catalyst structure and performance for the hydrogenation of CO bonds.

Selective hydrogenation of carbon-oxygen (CO) bonds is pivotal for the sustainable production of biomass- and CO2-derived fuels and chemicals. However, conventional heterogeneous catalysts frequently suffer from active-site sintering, poor product selectivity, and inadequate stability. This review presents a critical perspective on microenvironment engineering, a strategy that employs organic additives to precisely tailor the surface and interface properties of hydrogenation catalysts. We deconvolute the underlying regulatory mechanisms into four distinct functional categories: (i) geometric confinement, (ii) electronic modulation, (iii) hydrophilic/hydrophobic balance tuning, and (iv) acid-base property regulation. The effectiveness of these strategies was further critically evaluated across representative CO hydrogenation substrates-including dimethyl oxalate, CO2, and biomass-derived aldehydes-highlighting key mechanistic contradictions and unresolved questions that hinder rational catalyst design. We further identify the thermal durability of organic additives and the knowledge gap between laboratory-scale performance and industrial feasibility as the two most pressing challenges limiting practical application. This review offers forward-looking insights for the rational design of next-generation catalytic systems, aiming to bridge the gap between fundamental understanding and scalable hydrogenation technology.