The ionic characteristics and current rectification are investigated within a diverging nanochannel containing positively-negatively (PN) charged grafted porous polyelectrolytes, in this work. The underlying transport equations are numerically solved. The ionic selectivity as well as the associated transference number, net current output, rectification factor, and potential field are analysed by altering the bulk ionic concentration and bulk pH of the KCl ionic solution. A non-uniform electric field intensity is found in the diverging section of the nanochannel. It becomes apparent that the cationic concentration is higher in the acidic type of solution. The nanochannel is shown to be cationic selective for the acidic solution. The rectification factor is found to be much greater than unity when a diverging PN type nanochannel is employed. For the basic kind of solution, the rectification factor is found to be larger. The largest rectification factor has been determined to be up to 93.8 for bulk pH equal to 10. Therefore, the outcomes from this work are useful in designing effective current rectification devices.