Single Platinum Atoms Immobilized on Monolayer Tungsten Trioxide Nanosheets as an Efficient Electrocatalyst for Hydrogen Evolution Reaction

Monolayer WO3 center dot H2O (ML-WO3 center dot H2O) nanosheets are synthesized via a space-confined strategy, and then a single-atom catalyst (SAC) is constructed by individually immobilizing Pt single atoms (Pt-SA) on monolayer WO3 (ML-WO3). The Pt-SA/ML-WO3 retains the monolayer structure of ML-WO3 center dot H2O, with a quite high monolayer ratio up to approximate to 93%, and possesses rich defects (O and W vacancies). It exhibits excellent electrocatalytic performance, with a small overpotential (eta) of -22 mV to drive -10 mA cm(-2) current, a low Tafel slope of approximate to 27 mV dec(-1), an ultrahigh turnover frequency of approximate to 87 H-2 s(-1) site(-1) at eta = -50 mV, and long-term stability. Of particular note, it exhibits an ultrahigh mass activity of approximate to 87 A mg(Pt)(-1) at eta = -50 mV, which is approximate to 160 times greater than that of the state-of-the-art commercial catalyst, 20 wt% Pt/C (approximate to 0.54 A mg(Pt)(-1)). Experimental and DFT analyses reveal that its excellent performance arises from the strong synergetic effect between the single Pt atoms and the support. This work provides an effective route for large-scale fabrication of ML-WO3 nanosheets, demonstrates ML-WO3 is an excellent support for SACs, and also reveals the great potential of SACs in reducing the amount of noble metals used in catalysts.

Automated summary

Monolayer WO3·H2O nanosheets were successfully synthesized, and a single-atom catalyst Pt-SA/ML-WO3 was constructed, showing excellent electrocatalytic performance with high monolayer ratio, rich defects, and long-term stability. This work provides a novel approach for large-scale fabrication of ML-WO3 nanosheets and highlights the great potential of SACs in reducing noble metal usage in catalysts.