  Metal sulfate formation is one of the major challenges to the emissions
aftertreatment catalysts. Unlike the incredibly sulfation prone nature of Pd to
form PdSO$_4$, no experimental evidence exits for the PtSO$_4$ formation. Given
the mystery of nonexistence of the PtSO$_4$, we explore the PtSO$_4$ using a
combined approach of evolutionary algorithm based search technique and quantum
mechanical computations. Experimentally known PdSO$_4$ is considered for the
comparison and validation of our results. We predict many possible low-energy
phases of the PtSO$_4$ and PdSO$_4$ at 0K, which are further investigated under
wide range of temperature-pressure conditions. An entirely new low-energy
(tetragonal $P4_2/m$) structure of the PtSO$_4$ and PdSO$_4$ is predicted,
which appears to be the most stable phase of the PtSO$_4$ and a competing phase
of the experimentally known monoclinic $C_2/c$ phase of PdSO$_4$. Phase
stability at finite temperature is further examined and verified by free energy
calculations of sulfates towards their possible decomposition products.
Finally, temperature-pressure phase diagrams are computationally established
for both PtSO$_4$ and PdSO$_4$.
