Boron-induced growth of highly textured Ag (111) films with nano-tentacle structures for the electrochemical reduction of CO2 to CO

•DFT simulations reveal a deviation from the linear scaling relations for Ag-B.•Co-sputtering B with Ag facilitates the growth of Ag (111) twin boundaries.•The surface morphology of the Ag-B thin films consists of unique nano-tentacle structures.•A CO faradaic efficiency of 97.9% is achieved for the Ag-B catalyst. Ag is a cost-effective alternative to Au as a catalyst for the electrochemical reduction of CO2 into CO, but a reduction in the accompanying overpotential is required to make Ag viable. In this study we use B to modulate the catalytic performance of Ag towards the electrochemical reduction of CO2 to CO. Initial DFT simulations discloses a deviation from the linear scaling relations with the inclusion of B that stabilizes the *COOH intermediate while weakening the binding strength of *CO. A magnetron co-sputtering process is used to develop a catalyst based on B-induced crystal growth of highly textured Ag (111) films. Incorporation of B facilitates the formation of Ag (111) coherent twin boundaries, which gives rise to unique nano-tentacle structures. The Ag-B catalyst achieves a faradaic efficiency of CO production of 97.9% at −0.9 V vs RHE with a partial current density that is four times higher compared to pristine Ag. Thus, the inclusion of B into Ag offers a facile approach for circumventing the linear scaling relations, allowing for the design of electrocatalysts with high faradaic efficiencies and current densities.