4.8. Simulation details
The CASTEP code in Materials studio was used to simulate the electronic
structure and Gibbs free energy path of the catalytic model. The
generalized gradient approximation proposed by Perdew, Burke, and
Ernzerhof (GGA-PBE) was identified as the exchange correlation
potential. In addition, ultrasoft pseudopotentials are used in the
simulation process. The cut-off energy and MonkhorstPack mesh k-point
were controlled to be 500.00 eV and 1 × 1 × 1, respectively. Convergence
tolerance was considered to be an important parameter in the geometric
optimization process, which mainly includes the following aspects:
energy factor (5 × 10−6 eV per atom), maximum
displacement (5 × 10−4 Å) and maximum force (0.01 eV
Å−1). The DFT dispersion correction (DFT-D) was used
to further analyze the electronic information of the catalyst model,
which also considered the van der Waals interaction to improve the
reliability of the simulation results. The CoP (011) and CoOOH (010)
plane were used to further analyze the adsorption-desorption process and
reaction pathways in the HER and OER processes. CP2K/Quickstep code was
used for AIMD calculation. The exchange-correlation potential and
pseudopotentials were set the same as in Materials Studio. The cutoff
energy and van der Waals interactions were also considered, which were
selected as 400 eV and DFT dispersion correction (DFT-D3) respectively
in this module. The acquisition method of The AIMD simulations was
determined to be canonical (NVT) ensemble. Among them, the target
temperature and time step were set to 298.15 K and 1.0 fs, respectively.