CO Adsorption on GaPd—Unravelling the Chemical Bonding in Real Space

The electron localizability indicator-an efficient quantum chemical tool for analysis of chemical bonding-is applied to unveil the chemical bonding behind the CO adsorption on the (1‾ 1‾ 1‾ ) surface of the highly selective semi-hydrogenation catalyst GaPd. Refining the commonly applied Blyholder model, the obtained results are in excellent agreement with previous experimental and theoretical findings. The clean GaPd(1‾ 1‾ 1‾ ) surface presents unshielded negatively charged Pd centers and positively charged Ga species partially shielded by dangling bonds. The CO molecule adsorbs on-top of the Pd centers perperdicular to the surface, while no CO-Ga interaction is observed. The chemical bonding analysis results in deep understanding, thus enabling a cost efficient route to innovative materials by reverse engineering.