MXenes-like multilayered tungsten oxide architectures for efficient photoelectrochemical water splitting

Currently, the multilayer architecture is recognized as one of shining stars with exciting applications in environment and catalysis, energy storage/conversion, optoelectronics and so forth. However, different to the typical MXenes, the fabrication of layered transition metal oxides is still a grand challenge, since they are highly difficult to be exfoliated into multilayered structures, owing to their intrinsically strong covalent bond. Here, we report the controlled growth of MXenes-like WO3 architecture in the families of transition metal oxides with perfectly multilayered features, by tailoring the formation of precursor WO3·H2O based on the competition between the concentrations of WO42− and anions (NO3–, Cl−) within the solution. The as-built multilayer WO3 architecture has overall superior physical performance to conventional solid counterparts, and exhibits a remarkable photocurrent density of 2.3 mA cm−2 at 1.23 vs. RHE under AM 1.5G illumination, which is the highest one among those of WO3 photoanodes without cocatalysts/dopants in neutral solution ever reported.