Tunable Hydrogen Doping of Metal Oxide Semiconductors with Acid-Metal Treatment at Ambient Condition.

Hydrogen doping of metal-oxide semiconductors is promising for manipulation of their properties towards various applications. Yet it is quite challenging because of harsh reaction conditions and expensive metal catalysts. Meanwhile, acids as a cheap source of protons have long been unappreciated. Here, we developed a sophisticated acid-metal treatment for tunable hydrogenation of metal-oxide at ambient condition. Using first-principle simulations, we first showed that with proper work function difference between metal and metal-oxide, the H diffusion into negatively charged metal-oxide can be well controlled, resulting in tunable hydrogen doping of metal-oxides with quasi-metal characteristics. This has been verified by proof-of-concept experiments that achieved the controllable hydrogenation of WO3 using Cu and hydrochloric acid at ambient conditions. Further, hydrogen doping of other metal oxides (TiO2/Nb2O5/MoO3) has been achieved by metal-acid treatment and induced change in properties. Our work provides a promising way of fine tailoring metal-oxide via tunable hydrogen doping.