StrToUnicode C#语言如何将汉字转换成Unicode字符

public static string StrToUnicode(string str)
        {
            StringBuilder sb = new StringBuilder();
            if (!string.IsNullOrEmpty(str))
            {
                for (int i = 0; i < str.Length; i++)
                {
                    sb.Append( "\\u" + ((int)str[i]).ToString("x"));
                }
            }
            return sb.ToString();
        }