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A fully interactive Cu/C/H/O reactive force field (ReaxFF) was developed for the Cu-metal surface catalysis system following three steps: (1) re-optimization of the Cu force field by an extended training set including additional Cu cluster properties, (2) combination of this re-optimized Cu force field and an existing C/H/O force field, and (3) fitting of interactions between Cu and C/H/O with extensive DFT data involving the various binding energies and elementary reaction steps. In addition, we developed an algorithm to search the transition state (TS) of elementary steps, which is the first TS searching program based on the ReaxFF theory framework, and a new algorithm is proposed to create reaction paths and coordinate scans with highdegrees of freedom. The comparison of results of DFT and ReaxFF indicate that the developed force field is capable of describing the properties related to reactive interactions between the Cu metal and C/H/O molecules. To test this developed Cu/C/H/O force field, a series of molecular dynamics simulations were performed. In Cu/C/H/O surface simulation, elementary C/H/O reactions involving H transfer and H 2 /CHO dissociations were observed supporting the complex C/H/O interactions on a Cu surface.In addition, two Cu/CHO example cases relevant to the chemical looping combustion process were also simulated: metal oxide (CuO) generation from reactions of metallic Cu with glucose and hydrocarbon fuel oxidation using a copper oxide as the oxidizer. Our simulation results indicate that the current Cu/C/H/O ReaxFF is able to capture the reaction details and distinguish the redox performances of different fuels.

Solar water splitting is an eco-friendly technology to produce clean energy, but the water oxidation half reaction hinders the overall water splitting due to four electron transfer processes. Z-Scheme photocatalytic...

Molecular insights into graphene-catalyst surface interactions can provide useful information for the efficient design of copper current collectors with graphitic anode interfaces. As graphene bending can affect the local electron density, it should reflect its local reactivity as well. Using ReaxFF reactive molecular simulations, we have investigated the possible bending of graphene in vacuum and near copper surfaces. We describe the energy cost for graphene bending and the binding energy with hydrogen and copper with two different ReaxFF parameter sets, demonstrating the relevance of using the more recently developed ReaxFF parameter sets for graphene properties. Moreover, the draping angle at copper step edges obtained from our atomistic simulations is in good agreement with the draping angle determined from experimental measurements, thus validating the ReaxFF results.

It is still a challenge to develop an organic conjugated photocatalyst with a high O 2 evolution rate. Functionalization organic polymer photocatalysts is an effective way to enhance photocatalytic performance. In this study, a series of perylene imide polymers (PDIs) are prepared by introducing different number of phenyl groups at bay position of PDI, and the influence of the number of substituents on charge separation and photocatalytic activity is investigated. It reveals that monosubstituted PDI exhibits the highest O 2 evolution rate of 2524.88 µmol g -1 h -1 under visible light illumination without any cocatalyst. The excellent performance ascribes to the push-pull intramolecular charge transfer and the high crystallinity, which significantly promote separation and transfer of photoinduced charge. However, the O 2 evolution rate dramatically drops with the number of substituent groups increase because introducing more groups at the bay position of PDI decreased charge local excitation of the PDI core and occupied the O 2 evolution active site. In addition, it is found that increasing the number of electron-donor substituent groups would seriously destroy the crystallinity, leading to a decrease in the O 2 evolution rate. This study highlights a reasonably structural modification strategy to enhance the O 2 evolution rate of the PDI polymer by electron-donating group monosubstitution.