Preparing Rh6(CO)16 Via Rh(CO)2(acac) On TiO2(110) Surface As a Viable Route Toward Controlled Synthesis of Rh Nanoparticles

Two methods were employed to assemble Rh₆(CO)₁₆ on TiO₂(110) single crystal to investigate the importance of surface reactions on preparation of site isolated Rh₆(CO)₁₆ desired for controlled synthesis of Rh nanoclusters. First, by utilizing chemical vapor deposition (CVD) and second, by means of surface reaction of supported Rh(CO)₂(acac) on TiO₂(110) substrate at 373 K with the presence of CO  at 10^-7 mbar. “As deposited” particles were characterized by Scanning Tunneling Microscope (STM). Deposition from CVD of Rh₆(CO)₁₆  powder resulted in 24% larger particles in volume, on average, with larger diameters but smaller heights. In addition, this method showed more dispersed particle size range. In contrast, synthesis of Rh₆(CO)₁₆ via Rh(CO)₂(acac) produced smaller particles with 43% narrower size distribution. Subsequent annealing to 573K was performed to investigate the stability of deposited particles, which confirmed the high stability of assembled particles and ultimately the advantage of utilizing Rh(CO)₂(acac) for controlled synthesis of Rh nanoparticles.