In this work, we introduce in situ diluted (ISD) hydrothermal synthesis of a titanium-doped Fe2O3 photoanode and suggest a novel microwave-assisted surface attachment (MASA) method for fabricating an aluminium–titanium co-doped photoanode. The charge-carrier density of a hematite photoanode increases with Ti4+ doping, which offers lower bulk resistance. Through MASA treatment, Al3+ ions can be attached homogeneously on the surface of a Ti–FeOOH film from aqueous aluminium chloride. The charge recombination is weaker after the successful diffusion of Al3+ and partial formation of self-induced Al2O3, which acts as a surface passivation layer. The synergistic interaction of Al co-doping and surface passivation cathodically shifts the onset potential by 120 mV and enhances the photocurrent density to 1.32 mA cm−2 (1.23 V vs. RHE). MASA treatment not only improves the bulk characteristics of the photoanode but also enhances the surface injection efficiency which promotes water-splitting. The charge-transfer mechanism for the prepared photoanodes was also studied extensively.