Bifunctional electrocatalyst junction engineering: CoP nanoparticles in-situ anchored on Co3(Si2O5)2(OH)2 nanosheets for highly efficient water splitting

The development of promising bifunctional water splitting electrocatalysts through precise design of composition and structure is a challenging topic. In this work, a novel junction is developed consisting of pure-phase CoP nanoparticles in-situ grown on Co3(Si2O5)2(OH)4 nanosheets, denoted as CoP/CSNSs. Rely on the small adding Co2+ (0.1 mmol) in complex precursor, controllable synthesis of pure-phase CoP without impure phases is achieved, and the perfect nanosheet structure from support can be inherited, the CoP/CSNSs therefore shows the highest electrocatalytic performance for both HER and OER in 1.0 M KOH. Besides, the overall water splitting voltage of CoP/CSNSs(+/-) delivers 1.50 V at 10 mA cm-2, which outperforms that of the commercial Pt/C||RuO2 system. The preferable bifunctional electrocatalytic performance benefits from the optimized electron state of the adjacent dual-active centers, such that surficial CoP contributes to the dissociation of H-OH bonds boosting the Volmer step of HER, and Co3(Si2O5)2(OH)4 support contributes to OH- adsorption facilitating the kinetics of OER. Meanwhile, the advanced nanosheet structure provides more accessible active centers and more efficient charge/mass transport highway. In this work, bifunctional metal silicate electrocatalyst for water dissociation is designed and fabricated for the first time. The simple and effective phase-modulation and structure-control is a promising strategy for continually exploitation of multifunctional metal silicate electrocatalysts. The develop-ment of low-cost and highly efficient metal silicate-based electrocatalysts may create new opportunities for future development of renewable energy conversion technologies.