The electrochemical N₂ fixation to produce ammonia is attractive but significantly challenging with low yield and poor selectivity. Herein, we first used density function theory calculations to reveal adjacent bi-Ti³⁺ pairs formed on anatase TiO₂ as the most active electrocatalytic centers for efficient N₂ lying-down chemisorption and activation. Then, by doping of anatase TiO₂ with Zr⁴⁺ that has similar d-electron configuration and oxide structure but relatively larger ionic size, the adjacent bi-Ti³⁺ sites were induced and enriched via a strained effect, which in turn enhanced the formation of oxygen vacancies. The Zr⁴⁺-doped anatase TiO₂ exhibited excellent electrocatalytic N₂ fixation performances, with an ammonia production rate (8.90 µg·h⁻¹·cm⁻²) and a Faradaic efficiency of 17.3% at −0.45 V versus reversible hydrogen electrode under ambient aqueous conditions. Moreover, our work suggests a viewpoint to understand and apply the same-valance dopants in heterogeneous catalysis, which is generally useful but still poorly understood.

Hemilability is an important concept in homogeneous catalysis where both the reactant activation and the product formation can occur simultaneously through a reversible opening and closing of the metal-ligand coordination sphere. However, this effect has rarely been discussed in heterogeneous catalysis. Here, by employing a theoretical study on CO oxidation over substituted Cu₁/CeO₂ single atom catalysts, we show that dynamic evolution of metal-support coordination can significantly change the electronic structure of the active center. The evolution of the active center is shown to either strengthen or weaken the metal-adsorbate bonding as the reaction proceeds from reactants, through intermediates, to products. As a result, the activity of the catalyst can be increased. We explain our observations by extending hemilability effects to single atom heterogenous catalysts and anticipate that introducing this concept can offer a new insight into the important role active site dynamics have in catalysis toward the rational design of more sophisticated single atom catalyst materials.

Electrochemical carbon monoxide (CO) reduction to high-energy-density fuels provides a potential way for chemical production and intermittent energy storage. As a valuable C₃ species, n-propanol still suffers from a relatively low Faradaic efficiency (FE), sluggish conversion rate and poor stability. Herein, we introduce an “atomic size misfit” strategy to modulate active sites, and report a facile synthesis of a Pb-doped Cu catalyst with numerous atomic Pb-concentrated grain boundaries. Operando spectroscopy studies demonstrate that these Pb-rich Cu-grain boundary sites exhibit stable low coordination and can achieve a stronger CO adsorption for a higher surface CO coverage. Using this Pb-Cu catalyst, we achieve a CO-to-n-propanol FE (FE_propanol) of 47 ± 3% and a half-cell energy conversion efficiency (EE) of 25% in a flow cell. When applied in a membrane electrode assembly (MEA) device, a stable FE_propanol above 30% and the corresponding full-cell EE of over 16% are maintained for over 100 h with the n-propanol partial current above 300 mA (5 cm² electrode). Furthermore, operando X-ray absorption spectroscopy and theoretical studies reveal that the structurally-flexible Pb-Cu surface can adaptively stabilize the key intermediates, which strengthens the *CO binding while maintaining the C–C coupling ability, thus promoting the CO-to-n-propanol conversion.

Copper-based catalysts play a pivotal role in many industrial processes and hold a great promise for electrocatalytic CO₂ reduction reaction into valuable chemicals and fuels. Towards the rational design of catalysts, the growing demand on theoretical study is seriously at odds with the low accuracy of the most widely used functionals of generalized gradient approximation. Here, we present results using a hybrid scheme that combines the doubly hybrid XYG3 functional and the periodic generalized gradient approximation, whose accuracy is validated against an experimental set on copper surfaces. A near chemical accuracy is established for this set, which, in turn, leads to a substantial improvement for the calculated equilibrium and onset potentials as against the experimental values for CO₂ reduction to CO on Cu(111) and Cu(100) electrodes. We anticipate that the easy use of the hybrid scheme will boost the predictive power for accurate descriptions of molecule-surface interactions in heterogeneous catalysis.