fcc hollow sites. The γ-Al2O3 unit cell obtained from literature, where we determine the most stable surface at reaction conditions is γ-Al2O3(111) with 0.4 ML of OH* (γ-Al2O3(111)-OH). The *OH coverage strongly influences the binding properties of the surface, as *OH tends to block the acidic sites that are, responsible for γ-Al2O3 catalytic ability, as we will discuss in detail below. We note that the highest surface acidity of γ-Al2O3(111) leads to a tendency of its sites to be covered by *OH at reaction conditions (0.4-0.7 V vs. RHE). However, as we show in Fig. , key intermediates toward lactic acid adsorb even stronger on the surface, replacing OH* at moderate reaction conditions. Thus, the surface model of γ-Al2O3(111) is more representative than γ-Al2O3(111)-OH. For every adsorbate we mentioned in b, the chemical equation of the adsorption process is: